Being able to remove poison from a creature is a nice touch. I'm not really clear whether the healing will work on a creature as well, but if it does, it will make cards like overdrive or red nymph quite a bit stronger. In the case of overdrive, I guess the purify might override it (no pun intended) as a status effect, but in the case of red nymph/rage potion, there isn't anything to override.
The anti-SoSa measure is a great one, and a clever way of indirectly nerfing the card that needed nerfing above all others. I just hope the AI is good with it.
Increasing the cost and healing of the unupped one both to 2 is probably alright, given that both were done at the same time. I've never really liked using unupped purify unless I knew I'd be facing poison, or was fairly sure, whereas the upped one with +2 healing was enough I'd take more of a chance including it in FG/arena decks.