Robert,

It's my experience that a micro per pad is overkill. The most rapid drumming is still pretty slow to a micro. As prev. indicated, velocity can be derived from the portion of time the conditioned sensor signal exceed a given (or programatic threshold).

The MIDI requirement outgoing is quite simple, you might want to consider if you will allow incoming MIDI parameterization for channel of operation (typ.10), Note to pad assignment and perhaps for threshold per drum adjustment.

Another consideration, the major sin committed by drum pads is that of falsing when mechanically induced noise occurs (jarring the pad or stand noise). Roland implements two sensors; one under the pad, another embedded in the Rim. The RIM sensor is used to either cancel in the analog format or as a reference in the digital domain to discriminate a drum strike from mechanical noise.

regards,
p