Re: Bill Lawrence USA vs. Original Bill Lawrence
They were originally the same company as 9finger stated, I started using them back in the early 80s when they were made in Nashville before the split.
Now, I use the B&Bs, love those pickups, and I like the fact that they were made by the same guy that designed them. And as stated, they are warmer than the USA version (yes, I have had both), although the difference isn't huge. They are great pickups, but different, they are designed for clarity and not to boost/cut any specific frequencies, so they will amplify the natural tone of the guitar they are in.
FWIW, I called them with questions years ago, and Bill actually answered the phone, super nice guy and he will give you more info than you can process. Another reason I will support them over the USA ones. The USA company just has a cheezy kinda vibe to them.
And as Aryton said, Dime and Nuno have used both versions, I think both of them started using BLs before the split.
And FWIW, the "XL" originally was just the "Lead" version and there was also a "Rhythm" version. The Lead became the XL and a slightly less hot version became the "L". The R is the original Rhythm and the C was a brighter version with less output that Bill made for *EDIT* Ronnie Montrose *EDIT*. The C is a great neck pickup if you want a super clear, single coil-ish sound in a hb, but it is very bright.
Anyway, I'm rambling, great pickups, I prefer the "original"...