Once again, it looks like my tendency to apply things with my own interpretation without digging deeper is showing through, because it sounds like I don’t actually do reverse hypers the way Louie prescribes.
I pretty much strictly do controlled reps, holding a brief squeeze at the top, not trying to overly flex, then controlling down and letting the harness gently pull and give some spinal decompression. I definitely don’t do any heavy weight swinging stuff, I could see how that would have a higher potential for injury risk.
Having done both, I do think there are some advantages to controlled rev hypers over regular back extensions, namely that I find that on back extensions I have to focus more to force my back to work instead of my hamstrings, whereas on the rev hyper it’s almost impossible to not have your back be the primary mover. Regardless, I think the take home point is that you need to be doing something to directly strengthen your low back that doesn’t involve a barbell on your back or in your hands.