I have a Monster 700, or 7000 or whatever. Seems to work fine, but it rarely says 120 volt on the display which in itself is annoying, but even more annoying in that it's plugged into an AVS 2000 thing that supposed to be a voltage correcter.
I sent an email to Monster who said that the displays have a normal variance, and aren't always set up identically etc. For a combined $2300-2400 the freakin meters ought to say whatever I want them to!
In any case, it appears to work OK, but I can't say that I've had the same out-of-body experience with any of the power conditioners I've used that some report.