How useable do you find the extra outer key, and what do you use it for?
I’m working on my own TAIPO inspired layout, trying to make it more functional for CAD use, and for optimization of modifiers an extra key would be useful. An extra thumb key was my first thought though.
Good choice! I’m sure you can figure out a keymap, though it may take a bit of trial and error, but that’s the fun part of this hobby ;)