Had a chance to shoot the 17 and 19 on Saturday. Nice guns, they shoot like Glocks.
Only drawback, besides the parts comparability thing... that slide treatment is super super smooth and slick. Slipperier than the Gen3 nonstick pan finish. I'm half-expecting some sort of revision to address either the traditionally-tepid serrations, or the slickness of the coating. For the ECQC crowd, maybe it's not a bad thing, especially with the beveled slide, muzzle-side. It's gonna be hard to stop this gun at contact distance.
Also noticed some mild slide peening developing on the range gun, 200 rounds in. Maybe this is from the return to a 2-pin system? Given Glock's stated intent not to offer the platform in 40SW, maybe this won't be a problem.