I've thought about using 811A or 572B in a Simple SE - sort of.
My thought was to build up a low power Simple SE for 6Y6, 6W6, 6V6 or something similar and use an interstage transformer insead of an OPT, then use this Simple SE to drive an 811A or 572B output stage in class A2.
This would be basically the same thing as the A2 811A amp on the One Electron website.
I have all of the parts save the interstage transformers, and it should be a reasonably easy project since there are similar builds already out there, but I have a lot of projects to get to before this one.
Win W5JAG