I thought Alexi was playing Blackouts. What happened?
He only used them for a very short period of time around the recording of Bloddrunk, and partway through Gigantour. And I don't think it was even in all of his guitars.
Save for that, since being with ESP, Alexi's used HZ's (modded and otherwise).
EDIT: I think in a somewhat recent interview he said he's been messing around with his tone, hence all the experimentation lately. The Blackouts, the Krank amp on the Guitar Heroes album, the new JCM800, the active EMG's, back to HZ's, etc. It'll be interesting to see what else happens.