John -
The flouro the Iron Man and myself were talking about is called Varivas in 50# - it's a better leader material than SeaGuar (although I do use SeaGuar 30#), seems to tie better and is more abrasion resistant. It's what I use all the time now for a 50# leader.
Of course it ain't cheap either

, but then, none of 'em are.
The only place I've found it is at the Saltwater Edge here in Newport, but it may also be available elsewhere.