Been using a Twiddler for years while commuting - initially I made a layout based on Dvorak left hand only and found it both quick to learn and comfortable to use.
This layout only had a few MCCs, but I started feeling like they were giving me a speed boost and wanted to see if more were possible.
I wrote a genetic algorithm to try to cram as many MCCs as possible in an easy to remember fashion: I got 107.
As for speed: I've never been great. My old layout had me at mid 30's (in words per minute), this new one has me at mid 40's after a month's practice or so.
No doubt faster Twiddlers would do better.
Repo, for those interested: https://github.com/Geoff-Lillis/twiddler-oran-layout.