OMB Barrett - finally coming over to the dark side?
You're looking for a "torque sensing" rather than cadence sensing system. Are you looking to build a bike, or are you looking for something off the shelf.

Personally I just use a throttle because I like the precision of them (and I run low power). Since you are an acomplished biker, you might be happy with a low power assist for hills where it is basically an on/off system. The trick with ebikes is that they get heavy quickly - which has to be ballanced out with the hill climbing advantages...