@ Soriku
That's a straw man version of the "fanboy" argument, since FFXIII was originally made for PS3 anyway. Additionally, SE said long ago that FFXIII uses only 4 of the six SPEs of the Cell. Dual threaded PPE plus 4 SPEs equals six threads. Three dual threaded cores in 360's processor equals six threads. Though there are power differences even so, what SE did simplifies the conversion they knew they'd undertake at some point.
Plus, Versus probably hasn't had the resources poured into it *to this point* that XIII has.