Jazzy2040
WOW!!
I visited that almost 2 years long thread.
Well I have to say that it's more alarming than comforting as it raises questions that echo in my head.
Geoff is quite active. And I guess the result can work.
Why bother?
Am I nuts?
Why spend so much time on something that is supposed to save time?
May be to save time?
Several AZ Controller configurations was made for special needs. Even when you can effort 5k$+ controller, that does not mean its integration with anything is what you want.
It also can happened that you have something and do not want pollute your working space with something else in case the device can do what you want. That way A&H Qu preset was born (far from cheapest device...) and Yamaha mixer preset was born (if you have used something for years... you can be attracted to the peace).
BTW. while searching also if Reaper had a MIDI controller feedback possible, I found out that hundreds of Reaper users have been begging for this since 2012 and I didn't see that it was solved or addressed by Reaper's devs.
As with Sonar, Reaper developers suggest device producers write corresponding code. As Sonar, they provide corresponding API, for free. Big (if not most) money everyone pay for hardware controller ARE for software development and DAW get no single cent from that. Unfortunately producers ignore Reaper, as they ignore Sonar.
What is funny is that people pay $60 for a DAW, $600 for controller (worse $200 as a hardware device) and then complain DAW is not supporting it... Is that logical?
I can imagine that a global MIDI echo can have some devastating results but how hard can it be for skilled programmers to add a Checkbox in the parameters learn window to enable or not MIDI feedback ?
Especially in Reaper as every control has to be learned individually.
That will not work with 90% of controllers. It will work with some buttons and even less encoders, that is not worse the effort.
As feedback, devices in general expect NOT the same values as they send (f.e. MCU and compatible encoders, all colored pads), sometimes not even the same messages (f.e. Faderport), require special timing (Alphatrack, Akai pads) or special care in which situation the feedback is sent (most motorized faders). And that is not even counting "not controllers" such as Digital Mixers, which need special interpretation/timing in both directions.
So ALL good feedback, for any controller and DAW, is CODED specially for particular controller and particular DAW. In some DAWs that is possible in C++ only (with open API for Sonar and Reaper, with closed API for all other), in some with scripting languages (Ableton, Bitwig).
Anyway, this makes me appreciate more Cakewalk's ACT Midi Controller with its automatic parameters mapping even though it doesn't have either MIDI feedback capacity.(only AZ control has it all 
)
As you can guess from my signature, AZ Controller is going to be ported to Reaper
Not in next months, it will take quite some time (a year or so).