Re: Sharkskin: Magnum/GPX/Steelhead taper?
When choosing these lines, what is important on how far you want do drift your fly after it hits the water. GPX and Magnum lines are wonderful for delivering nymph rigs, then they can allow a short to moderate drift with good line control. The Steelhead taper is better for extended drifts. Its longer belly is much easier to manipulate to acheive that longer drift.
When I think high stick nymphing, I think shorter drifts. The GPX and Magnum are fine fits for that purpose.
If you are thinking of extended drifts (say 50+ feet of line out), I would get the Steelhead taper. On my Z-Axis 691-4, I use a WF7F Steelhead line. The extra mass helps turn over all the terminal junk.
As for the Magnum taper, I am not surprised that some like it over a GPX for indie fishing. It is designed to turn over bass bugs.