I've got ~20k miles with beads and had nothing but problems. 300-400k with traditional balancing and no balance related issues. All 33"+. I don't think they'd be out there if not successful for some people, but I am certainly not one of them.
Had them for awhile on my old TJ on 35's. I forgot what brand. I was surprised how tiny the beads were. I had problems with them when airing down. I think the tiny beads were getting stuck in the valve stem. I use an ARB EZ Deflater that removes the air valve. I went back to weights and never had another problem. As far as balancing, not that great either.
I used them with 33's on my old TJ and they really worked well. That Jeep rolled so nice after installing them. The TJ would sometimes get DW and the beads helped a lot. Perhaps well balanced tires can help prevent it from getting started.
Haven't tried them on my JLU but I plan to when I upgrade the tires. I don't see why they wouldn't work for 40's, they're used on big rig trucks. Just have to add more beads for bigger tires to compensate for a larger possible imbalance.
I have had good luck with balancing beads in my 37s. The sticking of beads in the valve stems means that you do not use the correct valve stem cores. They are different than the stock kind.