The 2x magnification is perfect for my 1:35 model when it comes to the paint.
The 4x magnification, well. This is only a max 1cm large circle on the left side of the lens, for me not really usable but I do not need it.
I can not say much about the durability of the batteries, but should probably hold for a while as there are only 2 LED's.
The two arms are very stable, however, is the thread on the third hand of plastic. Then I would have preferred metal.
With a mini USB connection or even a network connection to the power supply, and the thread of metal it would be perfect.
But even so highly recommended.