If by any chance you haven't heard of the Avenger products yet, as a quick summary: They are good quality things.
It is durable, and can take the beating of the time over the long long years while you will have it. Unless you want to test the laws of physics and put something really-really heavy at the end of this arm, or the on that is longer, than it should stay straight for a long time. If you decide to more than max out it's load capacity, do not blame the extension arm for the bend that will be in it afterwards.
It is quality stuff and if this is something that would serve your purpose, there is not better alternative.