Hey NJ,
I'll give you my thoughts on the adjustable nut... My Series basses have them and here's the deal; If you have the bass properly set up and the nut cut the way you want it then there is rarely ever any reason to adjust it. Less frequently than adjusting the bridge for instance.
The advantages of an adjustable nut are; #1, it's forgiving, in that if you try to cut the slots yourself you can get a couple chances to get it right (I know this from experience). #2, eventually the slots will wear and you may find you need to raise the nut. #3, if you change string gauges it can throw off the setup and you may need to re-slot and raise some or all of the nut. #4, you can get a replacement blank that you can recut and bolt right in instead of having to completely remove and replace a fixed one.
I like the nut to act like a "zero fret". In other words, on an open string the clearance between the string and the 1st fret should be the same as fingering the first fret and measuring the clearance between the string and the 2nd fret. This assures that the string is as low as it can be on the nut end without causing rattles and buzzes. And that in turn effects the feel of the action, and the intonation, all the way up the neck.
I have a graphite fretless which also has an adjustable nut (and no truss rod). I can't set it quite in the same way as I described above because I don't want the open strings to growl or bloom like the notes a bit higher. But frankly, that nut has not moved since 1980!
OK, too much information. I hope I addressed your question. Ha!
Jimmy J