If you want to "duck", sidechain kick and bass for example, I think you should try a non Nebula compressor.Something clean and sterile.You just want the effect not the sound.Nebula is more a tool for "color".Try whatever house comp. who come with your DAW.
I love the recent r.i.m. 165a and 168 compressors (haven't got drawher yet), a big step from what I was used to ITB. I've not seen a hardware sidechain compressor being used, but if its the same step forward, I'd love to have that ITB.(I produce house music) I was also thinking it might even be possible to give any Nebula compressor sidechaining, even if it's not possible with the hardware. Would be awesome imo.
Also from what I've been reading on the forum, we can expect even better compression with the upcoming Nebula improvements. So more and more compressors shouldn't be that far away. This is why I thought I would put up this feature request
You could use the ages old sidechaining-trick: Use a standard compressor-preset, send the signal to the left input, send sidechain-signal to the right input, use only the left output -> Sidechaining ! Works in mono only though.
*I've tried. From what I'm hearing both channels still trigger the sidechain. I don't know if this is the right way, but I've set the sidechain signal much louder so that it triggers the compressor. For stereo I've been using two at the same time, one for left and one for right channel. Getting some decent results with sidechainging to a kick with the 165 comp. Ducking reverbs also sounds nice with the nebula 168 comp (the big preset). Thanks for the tip