Just an update for you guys. I ordered a ProShift unit for my Aprilia and was told I had to measure the voltages of the specific bike at various throttle positions. Previously they had done this on a bike of the same model but not on my bike (I'm in Australia and they are in UK). So I had to get my dealer to do this, for which they charged me.
Then I received an email, completely separately, which I assume they sent to all of their customers, stating that if you changed anything to do with how the throttle worked e.g added a quick action throttle, you would have to uninstall the unit send the unit back to ProShift for recalibration. Incidentally I added an Alpha QA throttle to the HP4 and didn't do this and the unit continued to work (but they hadn't issued the note at that stage). I can only assume they've had some problems, and given the nature of the product it's probably important enough to share. So be aware if you live a long way from the UK where ProShift are based.