Just to clarify, are we talking about zero stop, or locking turret? They are two entirely different features. If it's zero stop you're asking about, then please continue to read.
NF zero stops are very good
Depends heavily on model doesn't it? Define good.
As in works all the time? Sure, but who's doesn't? The NSX line certainly doesn't come to mind as having an easy to use zero stop. You have to pull the turret, and index 4 uber-tiny screws, all covered in grease. Not exactly my idea of a good time.
Other designs are much better. Vortex PST zero stop isn't what I'd call good either. Remove turret and jack around with shims... yuck. However, in it's price point, that scope is still a leader due to it having that feature.
Kahles, S&B, and others where you loosen the hex screws in the cap, and then turn the cap without having to remove it, is a much better design. Still needs a tool though, and it doesn't "click" while you are doing this, so you've got to be careful to line up the turret markings precisely. Some can be finicky in that regard.
Premier tactical scopes on the other hand, you simply flip a lever, no tool required, and you maintain your clicks! In my opinion it is by far the best zero stop mechanism I've seen to date. I love everything about the turrets on the Premier's.
Oh, and thanks for the support Gminor!