Well, for what it's worth............ I just did this EXACT thing this past weekend. I gave up my G19 to my better half, and chose to go with a 34 over the 17.
I shoot CCI/Blazer thru my guns, no troubles. As far as the difference, the extra length of the slide on the 34 "should" give ya a little edge on longer range shots, plus it already comes with the 3 1/2 lb. trigger, ext. mag release, adjustable sights, etc. Either are fine, but I went with the 34. Keep us posted on your decision!
Mike