Haven't used it in HD, but on my PAL PS2 version, I've killed about half the Dark Aeons and Penance with it. xD

Never really experienced with the hidden payment system (where you can gradually build up favour with Yojimbo and get him to use Zanmato for less and less money; depending on the difficulty of the opponent you're facing), I just paid him millions each time to guarantee it. Gotta love farming the Monster Arena for pricey weapons.