i love mine, i have the plus, works great even without weights
worth the money?... depends. if you have a good set of bags already, then probably not. you can use it prone, but bags would still be better on the ground. but otherwise, for plinking, sighting in, and general bench shotoing, yeah, they're great
Shooting off of one doesn't approximate anything I'd want to do with a long gun so I don't find them useful. They change, at best, cheek weld and at worst your gun handling practices. If I had a gun with recoil I couldn't handle over some extended shooting session I'd get a different gun. Not that a lead sled can tell you, but absolute mechanical accuracy is also of little interest to me. I care far more about what I can do with a given rifle than I do about what 'it' can do.