Well, that gain is not directly from the LRB, but from a lack of loss due to the hopup, though I think you may have said that...
Cranking the (regular) hop to get nice and flat at the same power level does cause jams, I've tried it. However, once you get above about 420 fps, the LRB effect still works, but the gains decrease until you hit about 650 fps. In fact, after about 800 fps, the LRB only helps if you are using steel bbs.
I knock down my power levels below 400 fps for a reason, it is my belief that the bb holds the most stable path when it is traveling a little slower. This has been proven again and again in my own testing, I can take very inaccurate rifles and just bump them down to 350 fps and they hit spot on. Basically, you're right. It only matters how you deliver that bb, not how hard it hits.