I have had 2 original gibson PAF sets and played several more and all of these were like that more or less, well exept one set that were in a semi which were well balanced.
My bridge mule is less hot when compared to the neck also, allthough i wanted it that way initially and i even asked Tim to overwind the neck. Tim said the 'normal' set would have a hot enough neck pickup allready, so i guess Tim actually makes the Mules set as true PAF replicas as he knows how. Kind of stupid of me to persume someone who makes pickups would ignore PAF's being differently balanced then a modern set, but anyway, i probably just needed to be sure i got them the way i knew they should be in my way of thinking about pickups that is.
Same thing with the Gibson '57 PAF reissues, they did offer an overwound 'bridge' version though, the classic +.
Ive read somewhere that overwinding a pickup 5% increases the lows and mids output by 5%, but decreases the highs by 5%. The oposite happens when underwinding, well as an approximate offcourse. I personally think that would not be a good thing with the mules since i allready think the bridge could do with a bit of extra highs, still that also depends on the guitar etc.
Also, kind of nice to be doing anyway, in the early 80's alot of the hardrock guitarists set up their bridge paf way up against the strings to get the that specific 80's hardrock sound, i seem to hear that also in some of AC/DC's earliest records, meaning the very heavy stringload.
Later, i think in the mid 80's high output pickups took over quickly and a more modern balance was used more often, still higher gainlevels were possible with the more modern amp lines and so on....
Well at least this is how i have allways thought it was back then.