I am guessing you mean Monoprice not manoprice? Anyway I personally have had very good experiences with their wall mounts. I have a friend who bought a articulating swivel wall mount for his 50" plasma tv. I was skeptical about it being able to handle the weight but it is fine(still makes me nervous to see his tv 3 feet away from the wall). Good mounts for a very good price and their AV cables are good as well.
One Downside to the mounts:the lag bolts and mounting hardware can be of poor quality,read the reviews on any mount and people will tell stories of lag bolts shearing and screws being incorrect. Go to the hardware store and buy quality lag bolts.
I did purchase my mount at monoprice for the 70 732 series. I think the product code was 6663. Worked perfect for me. This is also the 5th mount that I have bought from them for myself and others. Never any problems. I have never utilized their lag bolts, I have a bunch of others that I know are industrial strength. I use their lags for other projects around the house that don't involve hanging $2k from a wall.
Monoprice is ok, but I have compared them with other companies like Sanus, Omnimount, and Kanto AV Systems. The problem with Monoprice, is that they advertise "weight weight weight", but versatility suffers. Most TVs now dont have to worry about the weight restrictions of TV mounts. All of the companies I listed have much better options when it comes to more versatility when mounting your TV
I've purchased 4 mounts from Monoprice, all worked great at less than $20 each. The lag bolts aren't top quality but way more than sufficient to hold the weight of today's TV's, even the 96 pound Sharp 70 incher. The 6663 is an excellent mount and works well at just ~$26.
I got the Monoprice 6517 for my LG 65" (100lbs). It cost more than the others at about $100, but you can pull the tv out by a few feet and swivel it left and right. And since I was spending $2K+ on the tv, didn't mind spending a bit more to secure it on the wall. I've only had it mounted for a short time, but it works great.
I did use the lag bolts that came with it. They looked solid and sturdy. But after reading what others posted, might just get some stronger ones at my local hardware store. What's another few bucks for added stability.
I asked this in another thread but I figure this one is best for this question. Which mount should I get that will allow me to put it in the corner of the room. I have found a bunch that will hold the TV but I don't know how much it needs to extend out from the wall to be able to get a 45° angle. It has been a long time since high school geometry but If I'm calculating it right I'm thinking about 23 inches minimum.