A little over a week ago I installed Ergon GP5s. I haven't had a chance to use them on long trips yet, but so far I love them for my 13 mile round trip commute. They offer a few more position an the GP3s, however I probably only use the positions that I would have if I had GP3s 95% of the time -- so you are probably fine with the GP3. That said, for me, I'd still go with the GP5s despite the extra money/weight if I were to do it again.

Oh, I should add, I normally ride with gloves and with my old grips (which really weren't bad for commuting) if I forgot to put them on I'd realize it pretty soon and want to pull over a put them on. Today I did almost my whole morning commute before I looked at my hands and noticed I forgot my gloves, so even in the "stock" position I find them to be very comfortable grips.