Today I found another issue in using Waves plugins in CbB that further highlights the functional issue I mentioned yesterday with the PRS SuperModels (i.e. which have only mono and mono to stereo versions of the plugins, no stereo version). I was using their new version of StudioRack, again on a guitar part. (Actually, it was a virtual guitar part since I don't play guitar. The only reason this is relevant here, though, is because softsynths tend to start as stereo in CbB, short of your explicitly configuring them otherwise.)
StudioRack is a plugin chainer, with presets at the plugin chain level. There are mono, mono/stereo, and stereo versions. One of the presets I was trying out started with one of the PRS SuperModels plugins, which was then followed by a parallel process (with multiple plugins that run in parallel in that rack slot), then a delay, then a reverb. If I used the stereo version of StudioRack, knowing that the delay and reverb would be stereo effects, then the PRS amp simulator was disabled, just as if it were a missing plugin. Thinking about this, it became obvious that it is because there is no stereo version of that plugin, so it was, in effect missing. If I used the mono version, then the PRS amp was there, but the reverb (RVerb) was disabled, because there is no mono version of RVerb. If I used the mono/stereo version of StudioRack, all the plugins were available, but, of course, CbB treated it as mono, so the stereo effects of the delay and reverb would not come through.
As for the more general considerations, most of what CbB does with mono and stereo interleave and plugins seems reasonably logical to me. There have been times where I've needed to force stereo operation on a mono track due to either an effect that was inherently stereo (e.g. chorus, Leslie, ping pong delays, etc.) or effects that simply behaved badly in mono for whatever unknown reason (e.g. an older version of PSP MixTreble used to get bad artifacts if frozen in mono -- that has long since been resolved). I'm not sure if I've ever forced mono (other than for checking mono compatibility, for example on the master bus), but, in general things have behaved as expected.
CbB's FX bins also give helpful visuals to see if plugins are outputting mono or stereo. In fact, this is how I first noticed the issue with PRS SuperModels' mono/stereo plugin. I'd had a stereo version of a distortion plugin ahead of the PRS plugin, and it clearly showed stereo output with its little tics. That was followed by the PRS plugin then Channel Tools, both of which showed mono output because CbB had forced mono from the point of the PRS mono/stereo plugin.
I just checked Waves' website, and the only DAWs Waves supports in general but indicates as not being supported for the mono/stereo plugins are CbB and WaveLab. It's not clear to me why they don't have a stereo version of the PRS SuperModels when their other guitar-oriented plugins do have stereo versions.
Rick