You aiming to get a manual?
I'd never look back to a 3rd gen unless there really was no other way of sticking to the 4th. Pretty hard to find one in good condition too.
I've always thought the 4th's felt considerably bigger and heavier than the 3rds but that may have something to do with moving into a wagon from a sedan.
I agree on getting a cheap 4th gen gtb. Way more refined, more reliable, easier to tune/mod.
Or just increase the mortgage and get a sweet sweet supercharger for the 3.0 and have some serious fun, sure the mrs won't mind