I mean, lefties exist. It's fine if they want to have left-dominant. And if fast 10-key numeric entry isn't important and you're a rightie, then that's fine too. It's just, in both cases, the exception rather than the rule.

I really liked the layer switching on the thumbs; the problem, as I mentioned, is that if you're not ambi and you have a low key count board, a lot of common stuff is going to be in layers, and preferably under your dominant hand, and that really only comfortably lets you use three layers (under your non-dominant thumbs), and it's just not enough.

But TLDR on my blog, the real killer of Miryoku for me was having the modifier keys (M/A/C/S) under alphabet keys. There's simply no way to time that s.t. it's not either causing false mods or slowing your typing down. I really can only see Shift being under a letter key not doing either if you're not a fast typist. Nobody types perfectly consistently. Maybe MAC alone works, with a long enough activation delay; those aren't used in speed typing. But shift has to be its own key, or shared with something uncommon, like brace/bracket or some other uncommon punctuation.