Thanks...
Tell you what I experience with my stock Fender tremolo. The ONLY string that gives me trouble is the low E. I've eliminated the nut as a problem. Under intense magnification, the winds (only 2 or 3) around the low E post begin to unwrap as the bar is depressed. Although this is very slight, you can see the entire wrap begin to rotate on the tuning post and this keeps it from coming back to pitch, as the ridges on the winds do not always fall back in precise alignment as they wind back up to pitch when the bar is released. This constant CW/CCW rotation during tremolo use has worn out my low E tuner.
I'm curious if locking tuners will help this anomaly, because it only locks the tail of the string as has zero influence over the wrapped section. Unless, with a locking tuner, you could simply use less wraps???
My tremolo's range of motion is from E to G#, so about a 9 semitone drop with the bar against the pickguard....
I'd be curious to know how far you can drop your guitar's pitch with full bar use and tell me if it returns to pitch after such a divebombing excursion...