I have the Gen 4 and I really like it, but I wish it had the rounded slide edges of the Gen 5; that sure takes the “blocky” look out of the gun.
Lefty...are you sure you have the back strap snapped in good at the top on the Gen. 4? You said it was weak and flexing, but the med. beaver tail back strap on my Gen 4 is very secure. It’s kind of a hard snap at the top, but once done it’s very secure; at least on mine it is.For me, it’s grip angle mostly. I do not like to use the weak/flexing back straps on the G4/5 series. Although I have used them on the G26/27 size subcompact pistols and they are better. I have to do the strong side trigger guard undercut on my Gen 4s but not the Gen 3s.
I also use the Glock “-“ trigger connector and the Orange NY2 trigger spring in my Glocks. I just like the trigger reset and trigger feel with this set up. Anyways, these setup seems to work best on the Gen 3s.
I do like the Gen 4s recoil assembly, for the G23/22. I can tell a big difference between the two generations in 40S&W.
And who doesn’t love that frying pan finish on the Gen 3s!?!?