Well, I dusted off the apple magic trackpads again over the UK bank holiday weekend last week and here I am again typing on them. This time I'm able to:
* type (of course)
* rest my hands without letters being typed
* mouse and single-click with the right trackpad -- lovely! (or was until I broke it a bit implementing holds using only speed of finger group to trigger leaving the hold state, which made fine motion a bit "sticky" -- I think I know how to fix that but the code needs cleaning up first)
* move the cursor with the left trackpad -- a bit annoying because I have not yet implemented "locking-in" of gestures, so my horizontal swipes turn into vertical ones quite regularly
* use 3-finger enter and escape taps (they are single-keypad gestures currently because I treat the keypads separately)
* use shift holds (4 fingers)
Not bad for 2 and a bit days work I think!
Very unrefined compared to the touchstream, and still plenty to do (bugs, half-implemented algorithms and kludges, missing features), but I feel like I'm "over the hump". That might be misleading since the details are crucial, but I'm optimistic.