There's a bit of random testing done on this body piece
on this post, which might help out a bit, in terms of how exactly it
MAY affect Stoneskin with cures.
Otherwise, dunno what else it might do. If I had more time to play, I'd probably have my +1 Body already :/ If anything, getting the +2 does net a 2mp/tick Refresh, which is useful outside of Abyssea, I guess.
I may rebuild my potency entirely if we can find more conclusive evidence though. If anything, the body is an excellent piece for Cures I to IV assuming you can make 50% potency again in the other slots of gear since not only are you maintaining capped cures, you're also increasing the power of the Stoneskin generated from them.