Now got max power usage more than halved, down to ~2 mA - again that's with scanning the keyboard, updating and refreshing the screen, and now also while running some floating point calculations in a loop, so I'm hoping this is near representative of actual usage.

The big power gain was mostly from shutting down the GPIO lines used for serial, which were backpowering the serial chip on the dev board ... the blue LED (which happens to be on the port I'm using for SPI clock) is still blinking away, and may at this point be a serious contender for reducing power usage with a swipe of the soldering iron.

Currently working on completing the keyboard routine and integrating it into uLisp so I can have a working REPL!