I too think that XIII will probably be a sort of techno-blend. Id usually not like that kind of thing, but im really liking that sped up violin in the FFXIII trailer, so who knows
Seeing as how I like most of the FF soundtracks, ill say which ones I DONT want it to be similar to.
FFIX - There were some really ace songs in this one, but it just wouldnt suit it.
FFXII- Again there were some good songs on this, but I wouldnt want another one.