As much as I like monoprice, I would be wary of using their articulating mounts. I purchased two of them for some older 50" plasmas a couple years ago, very similar to the one you're picking it, and they sag horribly under the weight, and the plasma weight is well under the rated capacity. To compensate, I have to adjust the tilt back all the way to its limit so as to keep the plasma parallel with the wall. The tolerances in the spindles that hold the arms is bad, and there's just movement that happens, plus the thickness of the metal is questionably too thin and there's noticeable give in it, too.
For my main TV, I couldn't wall mount, so ceiling-mounted using a Peerless mount. The difference in materials and build quality is significant. The Peerless mounts are easily far more sturdy and stable and solid (and heavier).
Now I may still use a Monoprice mount for lighter weight displays, or for cases where I wouldn't want the articulating arms and just needing something hanging off a brace.
So maybe I won't spend $300-$400 to mount a $500-$1000 display and would pick a cheaper monoprice mount, but I sure as heck am not going to quibble with it for a $3600 display. And back in the day I bought it, it was for a $8100 display, so there was even less question.
BTW, Amazon carries the Peerless mounts you linked to, if you needed a quick and easy source (Amazon Prime eligible, too).