I used the quikwall (kicked off the discussion above), it’s been over a year, and it is holding up just fine. I laid down the thin base layer of cement as per the quikwall instructions. Basically just followed their instructions.
Pretty sure it was a lot easier than mortaring the blocks.
Filled the cinder blocks with cement and rebar because why not? Plain old cement is cheap and it absolutely integrates the blocks.
I also used the quikwall for the outer shell of the oven, over the insulation. Once again, holding up just fine.