Why all the love for the 1940s style Superspeeds? Is there any real difference between the 40s SS and the 50s or 60s SS (other than cosmetic)? Does the 40s SS give a better shave, and, if so, why?
I've used both and to be honest, there's probably almost as much variation between individual examples of each style as there is between 40s and 50s. I do think the grip is better on the 50s, but I love to use my late 40s Milord, just now and then.
I have several 50's versions and also a 40's, and to me they shave very similarly. The 40's feels lighter in the hand, and has a less "grippy" grip to it, due to the knurling pattern and the non-flared tip, but the heads seem identical, so they require the same angle. I think for ME overall I get a better shave with the 50's, just due to the control I have over them, but the 40's one can yield a just-as-exceptional shave with a tad more care. You can't go wrong with either...they are both fun and great little razors that give fantastic shaves with awesome handling. Think Porsches (or maybe a mid-50's Jag XK-120 with the top down) zipping along your face...
I have a 40's SS, a 50's Red Tip, and a 40's Aristocrat. They feel different from one another, but I get similar results with all of them. Each is, in fact, a lot of fun to use. I don't think you can go wrong.
My 40's and my 50's SS are my two favorite razors. The flare tip with a crystal gives me hands down the best shave out of any of my razors, even with crappy technique, rushing and poor prep.
I also absolutely love my 40's SS too. A tad more difficult to control but it works wonders.