Have got a G2, as do lots on here. I think mine is great, but others would hate the shaft or loft. The main thing is this, a G2 that suits you will be far better than a G5 that does not. I can't imagine that any normal golfer would tell the difference between the two clubs, if they both match that individual.
Would imagine there will be bargins to be had with G2's being sold off to make space for G5's. If it were me I'd get a cheap G2, so long as the shaft and club loft suit.
Just my opinion :)