Rebooting into recovery using ClockworkMod Is there any big difference between rebooting into recovery using ClockworkMod and using Volume Up + Power button when wiping cache?
No, how you access Recovery Mode doesn't matter at all.  ROM Manager can pass arguments to CWM Recovery to (for example) automatically flash an update.zip file, but it's effectively no different than manually selecting that file to flash after entering recovery with the key combo.  Same deal when it comes to wiping the cache.