The Super 3 is basically all midrange, not much bass or treble. I don't know what the BKP equivalent would be. At the time they launched the PC signature guitars Def Leppard were using tons of racked outboard gear, wireless systems etc so maybe the pickup worked well with all that gubbins?
In terms of getting the Phil Collen sound, I'm pretty sure I've read that most of the guitar on Hysteria was recorded with a Tom Scholz Rockman! No idea what they've used since.
As Nick has pointed out, Collen didn't join until after High'n'Dry. I think their style would have changed anyway, with or without him, but it's by far my favourite Def Leppard album.