Guy writes:

My preference has been to
not use split shot due to the problems with casting and wind knots.

That can be a problem when using split shot. It has a hinge effect. Best way
to do it is to make a circle cast. Lefty Kreh demonstrated it once at a show.
When your fly gets down stream, simply pick it up and cast upstream in one
motion. It ain't pretty, but it works. No false casting involved.

Have you, or anyone, experienced a definite increase with the use of bead
heads compared to traditional weighted nymphs? (Yes, a loaded question).

I don't know, but I really don't consider using the bead an advantage. They
probably serve a purpose in some anglers bag of tricks, but I have yet to
really see a difference.