I have a PG 200.4 (200w rms x4 @4ohms) to power a pair of Polk SR6500 components

AND

a 10 or 12" sub

Ill have the PG amp bridged to give a single sub 400 watts rms..is that enough power?

what do you guys think?

will I be missing something if I opt for the 10 and not the 12 because of limited space? is there significant difference between the two sizes?