I can't remember the site where I read about this but it said, as you did, they had complaints about the thickness of the head and the ability (or lack there of) to shave under the nose. So they came out with the Slim. Personally - like many others - I use my Fatboy (G1) more than any other razor.
I prefer the FatBoy as well. Min is an F2 and shaves like a brand new razor. It's awesome. Never been restored or replaced, and its as if it was just manufactured. Awesome razors
That pretty much goes for most vintage Gillettes (or Gems, or Schicks) which have survived the decades. And I have had a couple of TTOs with wonky doors and such, one of the reasons I prefer the three piecers. Sent from my Nexus 5X using Tapatalk
@Marc Bagwell '58 was the best year for Gillette adjustables, IMO. If you get into collecting anyway. I'm trying to get my 58 collection done. It takes a considerable pile of $$ (relatively) to make it happen tho. It's also been pretty fun.
Actually, Ford only outsold Chevrolet twice in the 1950s. The 63 to 67 Corvettes were iconic. My folks raced a 63 Corvette in road racing. Greg W.