MPE Arpeggiator

Anybody here written an MPE arpeggiator or any other MPE effects that work with MPE input / output? Just wondering how you know what channels to generate new notes on. And what do you do with pressure messages etc for a not that may no longer be currently playing.

The best is maybe to not consider MPE in the arp but do like a regular MIDI arp but keep the channel of the key pressed in the note sent (the one they refers to either same or octaved versions) ?