peter - any thoughts on plating both sides of the edge finger? the doubled up connections make me feel warm and fuzzy... but perhaps you don't think it's necessary?
years ago, the first time i encountered a lunchbox in a studio, the owner had to re-seat the modules multiple times during the session, lots of intermittent problems.. ergh. perhaps that particular lunchbox was from the wrong side of the tracks... but i wasn't too impressed with these edge connectors at the time

but these day's i've caved in to the 500 series like everyone else... haha
you've done such a beautiful job with the layout, if you nail the front panel design i think you'll have MUCH interest, even from the non-diy world. as far as i know there's nothing quite like it out there.
BTW: dan - great work on the harrison module - i bet the layout is pretty tight for that front panel board!