Re: Locking nuts on std strat style guitars.
On a standard Strat, there is enough distance behind the saddle where the string can move that, if you had a locking nut, you'd never be able to keep the guitar in tune with much use of the trem. If you had a locking nut but no locking bridge or fine tuners, you wouldn't be able to touch up the tuning after you locked the nut down.
On a fully locking system like a Floyd, having the string locked just behind the saddle is a big part of keeping it in tune. If you're not going to have a locking bridge with fine tuners, you're better off with a graphite or roller nut, or just a really good bone nut and some lube to keep things from sticking.