Just a heads up for anyone else in the same position. I sat the 1st day assessments with Avanti and had been invited back for the 2nd day assessments. In the meantime I sat my remaining assessments with a different TOC, passing them all to enhanced.
I contacted OPC regarding my avanti assessment day and was told because I'd sat the MMI I'd have to wait 6 months to sit the avanti tests because they use a different type of interviews (CBI). Pretty frustrating on all accounts, especially as 1) I wasn't told this at any stage by OPC and 2) it doesn't make much sense if they're two different tests?
So save yourself a journey if you're in the same boat. Don't think I would've been told until I arrived for day 2 unless I'd contacted them myself.
Good luck to those still in the process.