One thing that isn't mentioned much (maybe it's not even that well known) is that the Contax G lenses (except for the 90mm) will focus closer than other rangefinder lenses, such as Leica lenses.
The 35/2 Planar on the Contax bodies will focus to 0.5m. In addition the autofocus mechanism of the G lenses allow the lens to physically move beyond infinity, and also closer than close focus. I.e., the physical stop on the near side is within the close focus limit and the physical stop on the far side is beyond infinity.
What this means is that when it is adapted to micro 4/3, the 35/2 can actually focus closer than 0.5m. I don't have my camera here at the moment to do an exact measurement, but I'm estimating it will focus to about .4m, maybe a bit less.
This is significantly closer than Leica lenses, which are typically .7m to 1m. The 40/2 Summicron C is .8m. The Leica lenses have physical stops at the close focus limit so there is no cheating possible. Also since most micro 4/3 lens adapters allow focus beyond infinity, this has the offsetting result of slightly increasing the close focus distance.
This set of facts makes a huge difference, at least to me.
IMHO the 35/2 and 45/2 are the perfect adapted lenses. Excellent corner to corner performance, close focus ability, reasonable price, fantastic Zeiss color and sharpness. And the 90 Sonnar is a steal for a fast tele, easily as good or better than any 90 Elmarit, lighter and much cheaper.