GGHT was the major hangup, although I had some problems with the FOB song and RttH. Keep in mind that I did all my career stuff at LilBro's place (w/exception of GGHT) over Christmas break, so I don't necessarily remember all my stumbling points. I'm basing this mostly on scores. (Also, I didn't want to break LilBro's strummer, and RttH is filled with violent triplets.)

I understand that FWD is It when it comes to Hard, and that nothing else in the Hard Career mode comes close to matching its difficulty.

Since I haven't tried any of these songs on Hard at all, I couldn't tell you which ones are markedly easier/harder than their X counterparts, anyway. ^^;