To me, the ultimate strat neck clean sound is from Eric Johnson's dvd "The Fine Arts of Guitar". I think that it must be an underwound neck pickup. SSL1 is fine but too smooth (6,4K) for my taste.
if its his old strat ('54 i think) its probably just under 6k with some heavy insulation, maybe 8000 turns give or take.
pe vs formvar seems (i this is obviously being very nitpicky) that the pe isnt quite as bright or as big on the bottom end but the pe seems more focused. there are a zillions factors going on including my shakey hands. ive never tried doing a bucker with formvar but the p90 i did worked out great but the coil was noticably wider