It depends on what you want to do... Weight and Vesa are not a problem, as you said yourself, if you just want to mount it flat on the wall. But if you want to turn your TV sideways, it won't be possible to do that much without pulling it out completely, because the angle is a problem with the wider TV. I have a 45-inch TV on it and I also have to pull out 20 cm for an angle of maybe 20 degrees to the wall.
Do you have a stable concrete wall? Then it's worth a try for the price. With a plasterboard wall, I would be cautious about extending it completely.