I’ve been gravitating to longer barreled 9mms for target shooting and plates (I’m not a competitor, just an old guy who shoots a metric ton of ammo). I too find better balance with the 5” to 5.5” barrels, along with better recoil control and firing cadence. I’m not sure that switching to a G34 would give me an advantage necessarily over my G17 but I suspect it would “feel” better if that makes any sense to you. Overall for me, trigger is more important than barrel length when it comes to shooting with a dot as I typically do on polymer guns. With irons, I definitely benefit from the longer sight radius - pretty significantly. Every 1/2” of sight radius takes about 1/2” off my groups at 25 yards.
The PDP as I have it set up now feels very different than my G17. Overall weight, weight distribution, grip and trigger all favor the PDP right now for me, and it shows in my groups. However, the G17 with the Timney trigger is now much hotter in my hands than it used to be and it sure can give the Walther a run for its money. Even without red dots, though, my CZ TS2 Orange and S2 Orange are still more accurate in my hands. And, they should be - they weigh about 3lbs and have -2lb triggers.