Have been using the UT22 with the Taipo layout for a while now and am very happy with it. (Nowhere near my usual speeds yet, but very usable for recreational purposes!)
The case is Bubbleology's own closed-source design, which he kindly allowed me to get printed.
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.