I'm a guy and I've been doing this for years; shaft and balls. It started as a sexy request from a partner way back when and I have found in the interim that women are generally very pleased with this sort of thing. They seem far more likely to spend time down there and I'm pretty sure you'll like that. You'll catch some crap from guys once in a while... locker room, jacuzzi, whatever... but the only opinion about it that matters to me is the woman I'm sleeping with and she's the one who sees it 99% of the time, so what do I care? Everyone else is entitled to their opinion and I am entitled to ignore it.
I'd never really considered the aesthetic angle re: making it look bigger. I guess I'd heard it in passing before, but it never affected why I did or did not shave. Oh, and her tongue on your smooth skin on your balls.... yow. Seriously, dude... try it.
As for the itching... yeah. We've all been there. I have to agree with everyone else that doing it regularly makes the discomfort almost completely disappear. In fact, you'll be moved to keep things clean just cuz it itches less.
It's part of my showering routine and I average every other day. Sometimes I'll go a week w/o doing it, sometimes every day for a stretch... just depends. If I know I'm going to be seeing the gf... definitely... otherwise it's just whether or not I feel like it.