Well, the thing I always had against Drain Punch on Mienfoo was that Mienfoo really isn't capable of taking hits; if she's getting hit, she needs to skedaddle. That's why Regenerator is so amazing on her, but Drain Punch is underwhelming. There aren't many situations where you think "man I'd love to keep my Mienfoo in, but she's low on health" and Drain Punch can come save the day. And outside of a situation like that, Drain Punch just feels useless next to HJK that almost hits twice as hard as it does (albeit with a 10% chance of KO'ing yourself, essentially).