Like others, I've noted that polyphonic aftertouch sent via MIDI to Origin causes zipper noise. As with pitch bend, I think that Origin doesn't smooth incoming MIDI performance control signals enough. Maybe a global 'MIDI smoothing' control would be helpful?
However, I've found a way around the zipper noise issue. Insert a S/H module, select aftertouch as input, set sync to off, set depth and rate to maximum and set glide to taste (18 % was a good setting for me). At the target module, select S/H output instead of aftertouch as mod source.
http://blom.to/synths/Origin%20DIY%20AT%20smoothing.jpg
