I have just installed a couple of the STRONG articulating mounts from Staub (SNAPAV) onto 65" TVs and the mount is a beast. Definitely needs 2 people to install even on smaller TVs but didn't notice any sag when the TVs were pulled out all the way (one TV is corner mounted so is always extended a bit.

Issue I found with it is unlike the Chief the articulating arms don't allow for full maneuverability (IE trying to get a TV perfectly into a corner). Other issue is the way it mounts onto the wall bracket. Its only a plate that's about 4"wide (it is Cast steele) but is kind of difficult as you have to place the bottom in then the top then lock the top in.

Other than the above two somewhat minor issues definitely a go to mount for a very good price.