Well - there were very specific functions that were required for the new version - including MIDI CC control and feedback.
This meant very specific project routing was required to ensure the correct data goes to the correct places. It also meant splitting up the MIDI hardware inputs and outputs - so each input device whether keyboard/controller requires it's own track which gets routed through either an input processor or passed through to the target track depending on whether it's a controller for use with the SK2 script - or one which isn't to be used by the script (eg main keyboard).
Having the SK2 connected controllers routed directly into a track means that you have to set up your Reaper preferences carefully - as any controller with MCU fader assignments cannot receive Pitch reset messages etc - so these need disabling in Settings.
Each SK2 connected controller also requires a dedicated feedback out track.
The main restriction on this setup - is that you cannot say use a controller that uses the same MIDI input/output as a connected keyboard - so if you have just one controller - with boths keys and encoders - then this won't work with the SK2 script - as if you connected the controller up to the SK2 script - the keys would no longer function as note inputs to a track. This is therefore only useful if you have dedicated controllers for tweaking as opposed to playing.
Now all this sounds really hard to set up - but actually - you select which hardware inputs/outputs are for what - and the setup is done entirely by the push of one Setup button.
Another requirement for it - was that it should work seamlessly with an XTouch or XTouch extender (or both). Actually - you can have up to 4 XTouch's/extenders connected at once should you wish (I've only been able to test with an XTouch and an XTouch extender - but in theory it should allow for 4 different controllers connected to the SK2 script). It also needs to work with the coloured scribble strips on the controller - and it does
- colours can be assigned to different parameters easily - this was not as straightforward as it sounds. EDIT - actually - it's possible to have more than 4 controllers - but only if they can be programmed to send different MIDI data messages. If you're stuck with fixed data messages (like the XTouch) - then 4 is your limit.
But it should work with any controller that output's standard MIDI - so any MCU or programmable controller should work fine.
Anyway - that's the gist - lots of other features but won't list them yet - it won't be suitable for everyone - and depends how far a user is willing to fiddle with their setup (one bonus for portable installs though!).
I'm not sure how long it will take to release just yet - still a couple of things to do and I've been crazy busy at work since the new year - so haven't had as much time as usual to work on things.