I quite like the idea of having my CB55 as a stand-alone drum machine, as per original DR-55..
How about implementing a sequencer on the arduino, interfacing direct to the CB55?
Store the patterns in an array in memory, but back up to a data file. Possibly even load and save named patterns. I'm getting ahead of myself here..
It would need some way to select a pattern (8 slots?), select a part (A,B,A-B), ON and OFF buttons, Tempo Control, Mode selector (PLAY/WRITE).
I already have an Arduino Uno with an LCD and buttons, I reckon I could knock together a menu-based control system.
No need to restrict the hat to two patterns, either - just treat it as another programmable sound.. Accent would have to take priority, and stay high until all sounds on that beat had finished.. just thinking ahead..
Now, where did I put that Arduino?