oh yeah i think, for such a great downtune (2 whole steps), u should have a guitar just for it, and use a .12 or something like that
if u only have one guitar and still plan on doing a drop C, well .10s are ur best bet, beats 09s, but it still be very loose...
u know what? haha just get a 7-string and capo the 1st fret... there u go! real C! haha