One other difference is the G3s come w/ the snap on dust cover while the G2s don't. If you like the covers, that helps justify the higher price of the G3s.
I think the only G3's I have are a 10rd and a 20rd. Everything else is G2. The one thing I do like are the window mags. I will pay extra for those. I've seen no functional difference between the G2 and G3 that I have. The 10rd stays loaded with some varmint stuff in the case that vermin shows up in the yard. And the 20rd gets the most use basically because it holds 1 full box and the shorter length I find kind of handy. I don't use my 30rd mags that often. Kind of wish I'd bought 20's instead because the 30rd ones have kind of just accumulated. But I never go to a range so I'm never preloading and transporting a bunch of mags. I'm usually loading up a 20rd and walking out the back door on a whim.