well, Vivian Campbell almost certainly did not play Bare Knuckle pickups, as they are a relatively new company (I think)...They would have modeled their pickup on his sound (very accurately if their other pickups are anything to go by).

As for the callibrated sets and such, as far as I know, the sets are just pickups that have been specially matched to one another (as the pickups are handwound and scatterwound, each is individual...not like Duncans and DiMarzio).

In my opinion, any BareKnuckle pickup you get will make you so happy...(once again, in my opinion) the best pickups out there