http://www.dimarzio.com/pickups/humbuck ... distortion
I've seen the same pictures from GFH sessions provided by Andre LaBelle on Facebook of the engineer with Vinnie's Washburn. It was also to my understanding that the current consensus was that they were Duncan PAF's. Maybe I'm just too young to be able to tell the difference, but what is the difference between a PAF sound and just a regular pickup sound, like, for example, a Duncan JB or Dimarzio Super Distortion.
Pafs have a different eq curve and,basically were the blue print for the other models born afterwards.It is a matter of preference about materila- some of the ones you've mentioned are made with ceramic magnets instead of Alnico,and this already makes quite a difference- output,eq and attack.Some people like hotter output pickups for rock and metal, but sometimes such pickups aren't great for play clean.Also,often high output pickups give a muddy sound when there's too much disrtortion.Lower output pickups need an extra kick to push the amp into overdrive but you get a lot of clarity.
For example, Zakk Wylde did state that paf's are great for rock blues, but when you play through distortion and platy fast 16th notes, you need the clarity of EMG's .(don't forget that also he uses different ouput tansformers and EV speakers in his marshalls)
Ace has used both the super distortion and also the JB.Bruce liked the JB as many rock players do.The super distortion was designed to help push the older amps into the crunch/overdrive area
For me, the difference is also in the attack of the note, the dimarzio-in painting with broad strokes,here- seems to have more attack.Personally,i prefer the Duncan's.