I'm with you on the upper bunk; those little chains look kind of sketchy. Probably fine for 65 lbs., but if I was going to use it on a regular basis, I think I'd install an underneath pipe support ala Boler.
I have since installed a support system consisting of chrome plated shower curtain rod holders which I mounted on each end of the lower bunk and the underside of the upper bunk. I then stuck a length of thick wooden dowel into the mounts. I have it so there is no weight
on the chains but they are only half an inch or so away so if the dowels failed then the chains will catch the bunk. It made it a lot stronger however the 9 year old son I have will only grow and the upper bunk will become very cramped for him. Time for a pup tent at that time. My 5 foot 7 13 year old however is very comfy on the bottom bunk and feels much safer with the supports so his brother won't come crashing down on him. Cheers