FF14 won't challenge the PS3's power at all. It's just another one of their lies just like all of the ones they told about FF13. You'd have to be really gullible to think that S-E could ever push the PS3 to its limits.
It is just a mediocre hack & slash after all so you might as well use Move to try & get some entertainment out of this fake Metal Gear game. It's not like the story will matter as it's just a spinoff that Kojima will ignore when he makes a REAL MGS game.