Jeff, good stuff as usual. Just wanted to share a little about a good multiband. Though I don't usually condone it, it's excellent for mastering if you know how to use it. For example, after I get a mix exactly the way I want it, I'll throw a multiband on to police everything. I use the UAD Precision MB and man....it's not only seamless, it's very transparent.
I could master an entire song (and have) with just it instead of an eq. Mind you, the only mixes I've done with it alone were my own....but man it sure did sound good. The object is to eq and compress all in one go while carving your mix. For example, just about none of my material will have sub lows under 40 Hz. I just don't need anything that low in my stuff. I do like to add sub harmonics of 50 Hz or even 60 Hz in. The MB I use controls that so well, it's crazy. You see it kick in but you don't hear it pump or clamp down.
Once I get that frequency just right, I can literally raise the level on that and it just enhances things like adding a frequency in an eq BUT....that frequency never crosses the line. I can do this with several frequencies and really have an awesome outcome without doing much of anything else. A lot of my pre-production stuff ends up being that way. Then I go back and listen to it later and say "oh wow, I remember how I did that.....this actually sounds quite good!"
But like I say, you have to have all the right stuff in your mix going on....and if you don't, you may have to pre-master and then do this stuff. But I really don't even do that to use the MB. See, this to me, is the problem with a lot of videos that show stuff like this. This may not work with a home recordist that is not up on his game. Like you said, it can ruin things quick.
That said, I use my MB on everything I master just to police the frequencies I adjust, or need to tame. If you have the right MB at your disposal, you have to really use it to the extreme to make it ruin something. OR...your mix is in such bad shape, it needs other things first before it even gets mastered.
To me, MB's will always be either used as a surgical tool for certain situations, for fine tuning something that is already in good shape or just as a police force that stops things from crossing that line. :)
-Danny