I don’t think that will be that strong. It is different from Cryptographer and serves a different purpose. So it could see play in certain spell heavy decks.
My favourite opener with Vaath is Crypto to get a super early 3 attack. This is with that minion not possible.
On the other hand it offers better value in the late game because it is not OG.
I don’t think there is a deck which has room for both minions, they aren’t that strong on their own and decks are always pretty cramped.