(mods:sorry for posting here, but i noticed it on a JS, so...)
don't know if i'm late or what, i just happened to setup a '06 JS1200 last night and when i got to the
locking nut i was like Wow! what's this!?!:
notice wider front and back grooves. seems like kind of an improvement of the TopLok III since the strings are now pretty well arched, following the board radius, and the grooves where the strings pass are way wider, kind of allowing them to "set" themselves in place. also, they *look* (but aren't actually) all the same width so that it can be used on lefties too. also, the fretboard-side edge isn't really flush to the board, but kind of "protrudes" (can't find better word) above the board, pretty much like those Earvana nuts, you know, but way less, just a hair.
don't know wether i'm right or wrong, just impressions. i'm sure Rich did noticed that, though.