IMO think a 904 replica will be really neat to look at and admire at car shows, especailly if someone builds one with a Carrera 2 engine, but I wouldn't want to own one. Reasons: no bumpers and really bad front end lift at speed. Didn't Butzi design the 904 body?
However, a really nice Abarth Carrera replica (like an Apal) would get my attention (and probably the rest of my money) - i would figure out a way to provide minimal bumper protection for one of those. I almost bought an original Apal last month for 10,000 Euro (it was in Belgium) but someone beat me to it.