No statistic for you but I can tell you that the 12mm of barrel length has far less to do with accuracy than the 12mm or so less sight radius. What you are going to give up with less barrel length is a little muzzle energy/velocity but likely not enough to ever be significant to you. The distance between the front and rear sights will almost certainly have an effect on your grouping though. You eye will not pick up movement between the front and rear sights as readily when they are closer together which will serve to open your groups up a bit. That coupled with a little less grip length on the G19 may make it difficult for you to group well out of the box. Of course with practice and familiarity you may be able to tighten them back up over time. If accuracy is your drive the G17 is a better choice. It will be probably be easier to shoot well and it holds a few more rounds in its stock form as well which is always a plus . My Glock 9mm is a G34 with a 5.4" barrel. I don't CCW so the compact 19 never made my list. If you really want to stretch out the sights look into the G17L.
A friend of mine shoots a G34 as well and put on a HUD red dot and removable butt stock (to each his own). Same basic pistol (identical barrell length) as mine but he nails 1lb. propane cans at fifty yds. darn near every shot, I'm good for one out of five maybe. Shooting my bone stock G34 he'd never hit it all. The difference being a whole lot more stable sight picture with his accessories. The longer sight radius on the G17 vs. the G19 will contribute to a more stable sight picture for you as well.
PS: Those 1lb. propane cans are always empty and never sitting on a rock next to the fire