I know about the welding, while I can weld I will most likely let a friend or club member do it.  The cage has never been installed so the plates have not been attatched.  From what I can see in the original phot that weld is fine its just a triangular glare.  Its hard to see in the resized photo. If I don't like any of the welds I have no problem grinding them down and having my friend redo it.  For the price I paid I'm not going to complain.  Don't know what you mean by main hoop?  This is, like a lot of full TJ cages, uses part of the stock roll bar.  Could you be looking at where things like the seatbelts or sound bar bolts in?