I wanted a stereo bar for a long time; but it was one of those things that I just kept putting off. I had seen the prices of some of the leading-name brands and decided I would take a chance on something simpler. I am pleased I have bought one because it reduces setup time (one fewer stand) and "creates" space, particularly when recording drums.
You don't get the angle markings on the Adam Hall Stereo Bar but that should not worry you, if you already have some experience of setting up stereo pairs. X-Y and ORTF are a cinch with this device. If you haven't done any stereo miking, there are plenty of videos available on the internet to help you.
The screws seem okay; they probably wouldn't stand up to being gigged every night for ten years, but my needs are smaller.
I often only use one overhead microphone on gigs, for my drummer, and most times we have a proper soundman anyway; so whether it's sturdy enough to stand up to being gigged doesn't apply to me. I bought this for my home-recording setup and I believe that it is more-than up to the task.
I think the theory is that mics in stereo should be matched pairs; but I'd suggest you go with your ears, not theory, if you do not have a matched pair; however, I would recommend using a pair of the same type.
If you record and you want to mike up in stereo, buy this; it's cheap and it does a decent job. Mine lives in my Thon mic case, which my wife bought me for Christmas.