I have a Scylla and a Skeletyl from BastardKb (the site linked above). The Skeletyl is a 3x5 keyboard with three thumb keys each hand, and I love the thumb clusters on it. Works perfectly with Miryoku and each key is very comfortable to press.

I'm pretty happy with mine, looks like this: https://www.reddit.com/r/MechanicalKeyboards/comments/p282ee... I like how the thumb buttons splay across the way you rotate the thumb, so you don't need to stretch/contract the thumb, which is awkward.

What do you like about your Glove80 thumb cluster?

My thumb rests at close to neutral position on Glove80 as well, at least compared with Advantage. I like that I can press thumb keys more by moving my arm slightly without having to contract my thumb tendons whereas Dactyl is more of a claw grip.