In terms of upgrade, yes it is, that's how we arrived where we are. Well, we were a single channel kit, so we also needed the PQ027! (£115)
The accessories page of the NVH shows the 4th Axis upgrade, PQ029, which is currently £289 (inc Foam Tray worth £29), verse £210 if you buy it all at once (no Foam).
4th Channel differences and applications, I think someone else who uses both 3rd and 4th Channels regularly (or the Pico team) are best, as sadly we've not had much need to use in anger, so sorry.
I'd be interested to hear some answers/feedback too, and outside of prop shafts, where the optical sensor would be usable, as we don't have that toy
I also noticed a Mongoose J2534 lead was now available as an optional part of the Kit, so would like to know which other J2534 PassThru leads were supported, or if any old ELM still sufficed (does the Mongoose have addition feature capabilities I guess is my question!)?
And finally, sorry, is the microphone capable of being used like a "first-look" piezo sensor, or am I barking up the wrong tree (we do have a First-Look, but was just curious)?
Half an answer at least!