I'm hoping this review serves valuable to anyone contemplating buying this plugin.
The main use I have for this plugin, and what I discovered this plugin does better than any other compressor plugin I have ever used, is for ducking frequencies. In other words, using it as a side-chain compressor. As of now, Dec 2017, there isn't anything like this except for the stand-alone program called SpectraLayers with a built-in function called Spectral Casting. The downside with Spectral Casting is that it's not real time...so that is a huge downfall. With MSpectralDynamics (MSD for short) you have surgical control of your sound, in real-time, whether or not you're using it in side-chain; however, IMHO its side-chain capability is its most powerful feature.
The price tag is a hefty one though, so it may not be for the amateur or music hobbyist unless you can budget this kind of price but I can now say, after having used it on several mixes now, that it IS my definitive choice for ducking frequencies. NOTHING ELSE EVEN COMES CLOSE. I would go so far to say that if you're a professional mixing or mastering engineer, you SHOULD have this in your toolbox.
It does a lot of other things other than ducking frequencies, but I'm so impressed at how well of a job it does at ducking frequencies, that I'm going to bias this review toward that.
You know that pumping effect you get from side-chaining the kick into the bass...well...you can actually eliminate that artifact with MSD. If you still want that pumping effect, you can dial it in if you're producing Techno but when you want a clean and natural fusion of competing frequencies, this is the definitive choice to get that result.
It has MS mode, and every variation of the combination of manipulating the channels that make up the stereo field. You get both meter and graphical analysis of the audio input and resulting audio output. There is just too much to mention what this plugin does both functionally and creatively that I would suggest downloading it, READ THE MANUAL, then test it rigorously on a mix or two, especially in side-chain for ducking. Then test out the other purposes for this plugin...including its most obvious mode...compressor. Lol.
To wrap things up, although this was a biased review for its purpose most impressive to me, I know it will be an essential tool in every pro studio. A great complement to this plugin is Melda's MMultiAnalyzer for seeing competing frequencies on the same analyzer. Ozone 8 also let's you see competing frequencies, but only two at a time...Melda has no limit AFAIK.