g for command (gui) and a for option (alt) are ok, but h for shift and r for control look bad in the configuration. l for caps_lock isn't great either. I don't likem/m for left/right_command mainly because in Vim M is used for Meta as a modifier, and on Mac that's equivalent to the option keys.

The lower/upper-case system for left/right modifiers seemed like a good solution for keeping modifiers down to a single letter but it can be hard to distinguish them, especially o and O, and I've found myself wondering why some mapping wasn't triggering because I didn't notice this.

Needs improvement.