One of my friends had a 770 with a
PAF Pro, Fast Track (1 or 2, can't remember), and
Tone Zone. I remember it sounding pretty good in all the positions, but think it was a pain to wire the "split positions" with essentially 3 humbuckers.
I tend to like the Blue Velvet--it is relatively high output for a single coil and can "hold its own" with hotter humbuckers. I've used it in combinations with Evolutions (basswood), Tone Zone/Air Norton (mahogany), Steve's Special/PAF Pro (mahogany), Super 3/FRED (mahogany), Breeds (mahogany and basswood), probably a few others, and it's never let me down yet.
--Brent