Sold my G2 set a while back (not because of the '90)
The 90 is an excellent lens, sharp and "Knacky" excellent Bouqet or however one might want to spell this.... I used mine quite a lot, one can get some good deals on 90 ties at this point in time, I would definately go for it.
(not specifically the 90 lens, this applies to all Contax G lenses, appart from the zoom one)