The following is copied for posterity from Reddit user 120inna55 (R.I.P.). Link
¶ Main Info
It's no secret, I've become a member of the "Streamline" cult. I've done a bit of research, so I thought I would share it here along with some images demonstrating the differences between the first generation and the second generation. I'll stipulate that the first generation are generally accepted to have been introduced in the 1930s and then re-released with some changes in the 1950s. These dates are estimates, and neither model has a date code.
My OCD dictates that I at least initially use parentheses to set off the moniker, "Streamline", because it's not necessarily correct. In fact, "Streamline" is more a reference to packaging than to the razor itself. Among others, the 30s and re-introduced 50s "Streamlines" were essentially named after their respective packaging/cases: "Ambassador", "Strop Outfit", "Jewel", and yes, "Streamline". Except for having either "Gem" or "Ever-Ready" embossing, the razors were the same, and only the packaging and accessories changed.
I won't go into the history of Ever-Ready and Gem (along with the overlap) as it's beyond the scope of this writing and there are plenty articles on the subject. Yet it is worth noting that in modern times, it's commonly believed that the "Jewel" was only with the "Gem" branding and that it was marketed to North America and, I think, Australia. That's a misconception as there are clearly shippers that show the "Jewel" to have the Ever-Ready branding. Particularly in the 2nd generation models, there's a lot of cross-over with regard to naming, packaging, and branding. In modern times, because the razors are all the same (and all made in England), we're at a loss as to what to call them because there's no way to prove the sets remain with their original accessories and packaging. Thus, it's generally accepted that calling the razor itself a "Streamline" identifies it.
As far as difference between 30s (1st gen) and 50s (2nd gen), the 30s were a little heavier, had a thicker neck, larger apertures, and closed grooves on the bar as opposed to the open slots of the 50s'. Additionally, the 30s had a notch on the back of the head where the 50s had a solid spine. In the case in which the razor was paired with a strop kit, the auto-strop on the first gen was devoid of text where the second gen had the following embossed: "Ever-Ready Pat Appld for - Made in England Automatic Stropper"
With regard to performance, I can speak with some authority on this as I have been using both models for about 2 months. The first gen gross weight is 82.8 grams (head is 33.4 and handle is 49.4). The second gen gross weight is 78.5 grams (head is 34.9 and the handle is 43.6). Frankly, I don't notice the 4 gram weight difference between the two as I'm using them. I do notice a significant decrease in blade feel when I go from the first gen to the second gen lending a slightly smoother shave yet no discernable sacrifice in efficiency. I wouldn't call either of these razors harsh, but the second gen has become my favorite in part because it's more forgiving. The other reason has to do with application. The solid bar along with larger apertures on the first gen seems to port the lather directly down the handle. The open slots on the second gen dispenses the lather right out the bottom of the head. In typical use, this may not be relevant. However, being a shower shaver, I do appreciate the lather being directed away from the handle. It's a small matter, but it does give more points to the second gen in my opinion.
I've only used modern Gem PTFE blades with these razors, and in theory, I may not be receiving the shave these razors offered in their day. There has been speculation that due to the thinner rib on modern rib-back blades, we get a slightly more aggressive shave than with the vintage blade. It was theorized that the thicker rib angled the blade downward slightly. It would be like "shimming" the back of the blade and reducing the gap. I have no intention of testing this theory, but it does make sense. Again, this is not my theory, but rather one I've seen cited in a few sources.
Like other key vintage razors, hype waxes and wanes. Ultimately, I really didn't expect this level of a step-up from my other shavers. After a single shave with the first gen, it had me contemplating why I needed any other safety razors, DEs or otherwise. Now, granted, my exposure to vintage SEs are limited to the 1912 and Damaskeenes, of which the 1912 has been my favorite. I've never tried an injector, so I can't speak to them. It's strange, though---even bittersweet---in that I really like my other razors, particularly the variety and aesthetics, but honestly, I don't have another razor that can even approach the efficiency and comfort of this razor. My desire to have some variety may be quelled by picking up a few more of these razors and having Delta Echo do their magic.
I don't know if Streamlines are necessarily rare, but they are sought-after. This is one of those razors that every wet shaver should have the opportunity to use. I really don't want to overstate it, but in many cases, I suspect it will change a wet shavers shave for life.
¶ Differences between the two models:
¶ The first gen is on the left. You'll notice the considerably larger apertures and grooved, but closed bar. The second gen on the right has open slots. imgur
The first gen is on the left. You'll notice the considerably larger apertures and grooved, but closed bar. The second gen on the right has open slots.
¶ Any finish difference noted in the following image is purely related to lighting. Both models have an impeccable thick chrome finish. In my search, I did have to look hard to find examples without brassing on the bottom plate, as the cast chroming resulted in this common wearing defect. Not a single one suffered from plate loss in the high friction areas. These two exhibited no plate loss, so I won't be having them re-finished.
Any finish difference noted in the following image is purely related to lighting. Both models have an impeccable thick chrome finish. In my search, I did have to look hard to find examples without brassing on the bottom plate, as the cast chroming resulted in this common wearing defect. Not a single one suffered from plate loss in the high friction areas. These two exhibited no plate loss, so I won't be having them re-finished.
¶ Assorted Images
¶ This image of the first gen demonstrates the split spine.
This image of the first gen demonstrates the split spine.
http://i.imgur.com/NbeySH6.jpg
Here's the solid spine on the second gen:
Here's the solid spine on the second gen:
http://i.imgur.com/6IYQdzS.jpg
¶ Here are a couple shots of the Ever-Ready "New Chrome Strop Outfit" packaging:
Here are a couple shots of the Ever-Ready "New Chrome Strop Outfit" packaging:
http://i.imgur.com/b6D8iVq.jpg
Here are a couple shots of the Ever-Ready "New Chrome Strop Outfit" packaging:
http://i.imgur.com/ETARX4q.jpg
¶ For purist collectors, this one is actually a mismatch because the razor on the left is a first gen, but the paired auto-strop has text on it which would make it from a second gen set. imgur
For purist collectors, this one is actually a mismatch because the razor on the left is a first gen, but the paired auto-strop has text on it which would make it from a second gen set.
¶ A few unimaginative images of the "Strop Outfit" case:
A few unimaginative images of the "Strop Outfit" case:
http://i.imgur.com/cHs5yHc.jpg
A few unimaginative images of the "Strop Outfit" case:
http://i.imgur.com/LUVSiih.jpg
A few unimaginative images of the "Strop Outfit" case:
http://i.imgur.com/ZDsfvW6.jpg
¶ Weights
¶ First gen head weight: 33.4 grams
First gen head weight: 33.4 grams
¶ First gen handle weight: 49.4 grams
First gen handle weight: 49.4 grams
¶ First gen gross weight: 82.8 grams
¶ Second gen head weight: 34.9 grams
Second gen head weight: 34.9 grams
¶ Second gen handle weight: 43.6 grams
Second gen handle weight: 43.6 grams
¶ Second gen gross weight: 78.5 grams
Second gen gross weight: 78.5 grams
¶ Glamour shots
¶ Glamour shots of the first gen:
Glamour shots of the first gen:
Glamour shots of the first gen:
Glamour shots of the first gen:
Glamour shots of the first gen:
Glamour shots of the first gen:
Glamour shots of the first gen:
¶ Glamour shots of the second gen:
Glamour shots of the second gen:
Glamour shots of the second gen:
Glamour shots of the second gen:
Glamour shots of the second gen:
Glamour shots of the second gen:
Glamour shots of the second gen:
Glamour shots of the second gen:
Glamour shots of the second gen:
Glamour shots of the second gen:
Glamour shots of the second gen:
Glamour shots of the second gen:
Glamour shots of the second gen:
Glamour shots of the second gen:
Glamour shots of the second gen:
Glamour shots of the second gen:
Glamour shots of the second gen:
Glamour shots of the second gen:
Glamour shots of the second gen:
Glamour shots of the second gen:
Glamour shots of the second gen:
Glamour shots of the second gen: