jbraner
I'm not sure how Melodyne works as "just a plugin" - but you might have to edit parts, without hearing everything else playing (?)
Melodyne needs the whole "clip"/"region" to give you good results. So it has to receive material first.
Only this process is significantly different with/without ARA:
* without ARA, you "record" into Melodyne the peace you need, by playing the material (VST support sequential data processing ONLY)
* with ARA, the material is transfered like a "file", so no need to wait for real time playing.
The rest is the same: once the material is inside Melodyne, it "parese" it. Then it can produce the sound like a normal VST, on "its own" even when the transport is stopped or in sync with Sonar (simply ignoring its input and using parsed/edited information on its place). BTW the syncing can be broken in recent Sonar (
http://forum.cakewalk.com/Melodyne-clips-not-playing-in-sync-m3634843.aspx).
Remember all that weird problems with Melodyne at the beginning? For Sonar one bug more, one bug less was never a show stopper, the functionality was released. Reaper people do not like that...
I hope the technology is mature now.