I bought a used 812 and a garbaruk cage, and ordered XT 11-46 cassette. So trying that setup.
The 820 rear derailleur won’t work as an 11 spd on when paired with 810 1x11 shifters? As that would be a great upgrade.
Assuming I get 1x11 11-46t working, then I can’t see enough benefit to upgrading to 12spd.