When I met Paul at a meet and greet a few years ago, he touched briefly on the brass inserts which at the time was still fairly new. He said something about the string coming in contact with as much brass as possible would result in even less "subtraction" to the energy a player puts into the string. Hence the move years ago to the brass posts on tuners.
There are a few production stories that involve meeting deadlines that are now marketed into gospel as a tone quest enhancement. The tuners with no chrome is one one of them. The Santana no backplate/route, is another.
If Brass is "all that", it follows that we should have a Brass nut. The nut defines the tone at the head stock, not the chrome on a tuning peg.
I would make a bet that the cheaper Klusons on the 594's are now used to offset the cost of the Nitro finish/process.
Remember, they are are manufacturing company and economies of scale come into play as any other manufacturer.
A lot of what PRS has done is Lean Engineering. Taking cost out of a product, and if it is a noticeable change, make a good marketing strategy out of it. When they took the chrome off the tuner pegs, it wasn't for tone. Chroming metal parts isn't exactly cheap. But if you believe that you can here the difference, then you will.
Vintage Klusons are cheap tuners. The "tweaked tuners" were silly IMHO as the shaft is still connected to the button, and therefore the whole tuner still vibrates.
I own around 40 PRS guitars, 3 PRS amps, and 5 PRS Cabs.
I am so tired of people stating that Paul said this or said that. "Paul said it and therefore it must be true".
If you can take cost out of a product, and make it better, than all the better.
However, they have an active cost cutting program to be sure, as well as they should.
I am now at a point in my life that I just don't want to pay $4000ish for a 10 top 594.
I have a SC-245 and an SC-58 (Artist Package), and I love them. Not to mention a HB DC and an HB singlecut.
NOW, I have to run out and get new ones???? Wow.......
The magic is always in your fingers. Not in a tweaked tuner with plastic this or that or reduced metal, etc....