I have a gen4 G23 and G27. For me (odd as it may sound), I like the mag release on the gen4s a bit better. The adjustable backstraps are nice, but not a deal-maker or -breaker for me.2 month old thread... but whatever, I like the Gen 3s better than the 4s. Someone else up there said it too that there have been some recoil spring problems with the Gen 4s in the past... I just subscribe to the whole "if it ain't broke, don't fix it" mantra...