The only draw back would be if your RAM is less stable at higher clock speeds. Because there is little difference between DDR3 memory at different speeds a slower setting that leads to more stability would be better.
and if the i7 doesn't have an FSB, then what else is there other than a QPI
Yeah. technically both AMD and Intel dont use fsb anymore (since Hypertransport and QPI are actually new tech), but saying there is no fsb is nit picking. Thats like looking at a hot dog and saying "no, thats a sausage and if you call it by anythin else i wont acknowledge you"