I think I would if I were in your position, I'd want a second opinion.
I would certainly ask for a second opinion, just to be sure. But what if the new doctors say no problem and then the kidney actually can't be connected properly (meaning the Vegas doctors were right)? I don't want to discourage you, if you're brother is still willing (and by the looks of it he is not only willing but insisting!), I would definitely run another series of tests. It can't hurt.