I have used the old ones for well over ten years, and have yet to have one move in any way. And, yes, I have jammed on them pretty darn hard. Especially on the MFS at low water. I just put the new ones on my new raft. I like the nylon bushing for the oar lock, and they also have added ribbing to the surface that is in contact with the side rail, so they really shouldn't move. I've never seen anyone break a U-bolt. I have stripped a lock nut on one once. I have used both the NRS and the speedrail type oar towers, and I prefer the NRS. They are easier to adjust or remove, they stay put, and they don't leave divots in my frame side rails. I never had any issues with the speed rail towers, just liked the NRS better. The new NRS towers are noticeably lighter and very nice looking as was said above.
"We are all visitors to this time, this place. We are just passing through. Our purpose here is to observe, to learn, to grow, to love....and then we return home."
Australian Aboriginal Proverb