I love locking tuners cause I do a lot of bending but being on disability I can't afford Sperzel's. In fact that's how I discovered Guitar Fetish.
I've yet to have any real problems with any of the tuner sets I've bought from them.
Backlash is such a pain in the butt. Especially on stage when you really don't wanna spend more than about 10 seconds tuning your guitar.

Breaking the high E. I don't know how many times that has happened. I dd find that for me using locking tuners that lock from behind tend to break them less than the ones you use a coin to lock from the top. I always over tightened the top locking ones and since my high E is a .009 it's very easy to break.

Providing there were no other issues to cause tuning lose once I switched to locking I could go all night without having to tune.