If you really think how many games are made for x86_64. Even on windows there is no difference. I dont find it trouble as long as the libraries tend to work. Hard-drive space is pretty cheap these days...
And related to AMD thingy. Just bought new HTPC few weeks ago and upgraded with it this week. All full of AMD O.o (well basicly cause i thought that 6670D would have been fast enough to run my rocksmith under windows but no

) But im using mythbuntu on it too so hoping that AMD will get those linux drivers rolling atleast.