Can't help with that particular outlet, but I've never been accused of holding back on opinions, so...
First, not sure why the box has to be 'perfect' since it is hidden behind the TV. As long as it is clean and functional, it should be form over function.
Second, and much more important, I always say that you should separate the power and the low voltage signals but at least one stud. Never put them in the same cavity as that is just asking for crosstalk issues.
Third, I have never been a fan of low voltage outlets that end in sockets. I prefer the ones that have the 'hairbrush' style where you can pass a cable through. My reasoning is that any place you insert a connector is another opportunity for a failure. Most cable issues are actually connector issues. I would much rather string a longer cable directly from the TV to the AV receiver, or BluRay player.
Take it with whatever grains of salt you choose, but the above has worked well for me.