I guess it's a matter of what we're used to. I've used Sonar for years, and the Piano Roll View was designed to be the heart of MIDI, as it is in most other DAW software, and it really is exactly that. I Live in the PRV. CC data is mostly recorded in real time, and the data is seen there in the PRV, graphically associated with the notes so it's all perfectly clear. And of course hand editing can be done there. Working in the Track View and changing all that to envelopes would be really clumsy for me - I've experimented with it and it's more like drawing a picture of what I want instead of just Doing what I want directly.
I dunno, I don't use Reaper, but I've heard MIDI implementation is behind other programs. That could be part of it.
Reaper has piano-roll just like Sonar, with cc-lanes below, but the editing is not as mature as Sonar. But, not that big difference.
Maybe I wouldn't like to use track-envelopes, if I'd tried it, but it sure would be handy to have instant cc-learn on the parameters.
I guess Sonars ACT is not working with Aria either for the same reason, right?
Well, I've programmed my Korg NanoKontrol, so I'm fine
You could use ReaControlMIDI for CC's as well, which is provided with Reaper, but ReaControlMIDI only handles CC's and not Aftertouch, which I need for GPO/GWI vibrato control.
Please excuse the super-big screenshot, but this is how I've got it set up.
I set up JS: MIDI/Automation_to_MIDI as an FX on each midi track I need it for (in the screenshot, it's the Slide Whistle instrument).
The plugin allows automation of Aftertouch, Pitchbend, and two CC values. The controllers I'm going to need for the Slide Whistle are Vibrato depth (Aftertouch), Volume/Expression (Mod Wheel, aka CC1), and Vibrato speed (CC17). So, I set Controller A to CC1, and Controller B to CC17.
Make sure the MIDI channel is set properly (in this case, 3). Many a time I've wondered why the controllers are doing nothing before I realize I left it set on the default of 1...
In the envelope settings for the track, I enable envelopes CC A Value, CC B Value, and AT Value. That'll pop up 3 sub-tracks where you can shape the envelopes to your heart's content. In the screenshot, the green envelope controls aftertouch value and hence vibrato depth, the blue envelope CC A value, which is CC1 and hence volume/expression, and the purple envelope CC B value, which is CC17 and hence vibrato speed.
If you need to automate more than 2 CC's, load up as many instances of Automation_to_MIDI as you need to handle them all.