I've got a Gen 2 G17 and a Gen 3 G34 although I've never fired a .40 Glock so I can't really speak to the differences there. I can shoot the G34 noticeably better than the G17 past 15m or so, and from 15m in I've found they're about the same. I was surprised at the difference in the feel--the G34 points just a little bit slower than the G17, but, for me, it wasn't objectionable, just different. I like overall feel of the 5.3" barrel, not too muzzle heavy but nicely balanced, and the 3.5lb trigger helps with the longer shots. Overall, for a typical match with a mix of ranges from 7m to 50m, my scores are about 10% or 15% better with the G34, with most of the improvement at the longer ranges.