Lock nut with a Floyd or equivalent.
Std nut on everything else.
Roller nuts are nice if your whammy a great deal, and they might save you on buying new sets of strings in the long run. They almost can't wear out, like a nut will, either.
is it true that with a lock nut, when a string does slide back it'll be "locked" out of tune. or does this never happen? which is my biggest concern, and won't a normal nut wear down after heavy use?
what kind of vibrato system ?floyd rose -locking nut if you go dive bombing,fender style -special nuts not neccasary (try pencil lead if its sticking)bigsby leave it straight ,hope this helps
is it true that with a lock nut, when a string does slide back it'll be "locked" out of tune. or does this never happen? which is my biggest concern, and won't a normal nut wear down after heavy use?
The whole idea of the locking type nut is to completely eliminated the possibility of nut error when using a whammy bar. If the strings are locked at the nut, there is no sliding of strings though the nut. This does completely eliminate nut wear. As someone said earlier, the "v" shape of the locking nut as opposed to the slotted i.e. tighter fitting nut can cause a little vibration deadening.
Any of the three choices induce some trade off of durability to high tunability performance.
I would say if you EVER dive-bomb your guitar, you want a locking nut.
If you use vibrato quite a bit, get a roller.
If it's very occasional use, a good bone nut offers about the best tone/performance available by today's standards.
Locking. (for dive bomb use). Gentle vibrato: roller. I am glad to see that some others have noted a slight tone deadening (sp?) with a locking nut. Could you help that by having the groove more U shaped than V shaped ??
You can get pretty crazy with a graphite nut and locking tuners. If you don't routinely go so slack that you're in danger of popping a string out of a nut slot, you can get away without a locking nut. The locker will be more stable, but if you have a phobia about allen wrenches, you could live without one.