John Birch had the row of screws idea in his pickups in the 70's (look at Tony Iommi's old SG). My bare knuckles sustain as much as I want (I can go make a coffee, read a book, come back and they are still ringing :twisted: ).
I think most of the sustain comes from the interaction between the guitar, pickups and amp. With my valve amps cranked, there is plenty of sustain (even on my stereo 3 watt!).
I have never really gone for the tone of blade pickups for classic rock. They always seem ok for clean, but too metallic when driven. I know a lot of people use the hot rails, so I am probably looking at it differently to other people, however for me the regular pickups give a great sound.