I love the RTF2 17 and 19. If I could only have ONE Glock it'd be the Glock 19. This week I adopted the 36 (.45 ACP). The recoil is not horrible on the 36 and it's slightly thinner and shorter than the 19. I rented the Glock 30 too and it was a pleasure; however, too bulky for carry in my opinion. This was my first experience with Glock .45. Hopefully a Gen4 30 is in the works.
My grip is less secure on the 36 (than my 17/19). I just ordered a Talon grip and a "plus zero" magazine grip extension to hopefully create a RTF-esque grip. Another cool thing about similar sized Glocks is that holsters are interchangeable.
I feel everyone should have at lease one 9mm in their Glock arsenal if anything for the cheaper ammo. Also, in a natural disaster or apocalypse those 30 round magazines might come on handy!