Many folks use a single midi track for sequencing their drums, but have each kit piece routed to a separate audio track, in order to maintain complete sonic shaping control over each piece.
If you end up sequencing up each kit piece on a separate midi track, I would still suggest using a single instance of the drum synth, as it can happily respond to multiple midi tracks at the same time, for different kit pieces. I do not not actually recommend putting each kit piece on a separate midi track though, because it becomes a giant nightmare to adjust things like a roll - if each strike is on a different track, I would go bonkers in no time.
Bob Bone