After hundreds of dollars in repairs on my gear due to a failure of an electrical box exterior to my unit, I decided that operating without protection was not an option for me.
The Tice Elite IV power conditioner I use in my home theater seems to result in a clearer picture on my set. I also use an Audio Magic Stealth Matrix Mini conditioner on my main headphone amp, with a rather dramatic increase in instrument separation and dynamics.
I've got Monster power conditioners all over the place, and they seem to reduce the noise floor wherever I use them. So, I've come to the conclusion that I've got dirty power, and that any compression I might be hearing is overwhelmed by the perceived increase in dynamics with noise gone. Since I got good results with the stage 2 filtering in the HTS1000 and HTS2000, I've avoided attempting to upgrade. I don't know if the higher level conditioners will sound better or worse, and most of the time I prefer to stick with something that I know works in my particular conditions.
I've also got a Monster AVS2000 on my den setup. That's not a conditioner, per se, but holds voltage at 120v with an output of 15 amps. If that's not enough to drive a headphone amp, something is wrong somewhere. I've also noted that it's common for my home voltage to approach 130 v in the evenings, so the Monster is looking good right now.
The only conditioner I've used that produced audible compression was the Brickwall (I forget the model, but it's the audio one). I've relegated that one to my computers.
Bottom line is YMMV. You're not really going to know how any particular conditioner is going to work in your system until you try it.