I will say again that I can't really offer much of a comparison between singles and doubles, as by law here in British Columbia I have no choice. What I can do, however, is relate how we deal with some of the issues.
As Per notes, the short shank singles greatly reduce the number of fish that "fall off" on the jump due to barbless hooks. Given the chance to do so, I will fish barbed hooks. This only happens when I fish trout in lakes, to go barbless leaves me feeling a little hadicapped. As for steelhead - I have no choice - so I make do. When I fish Washington State rivers I still fish barbless, I guess it just becomes a way of thinking - it would feel like I was stealing or cheating if I used a barbed hook. Like I say, after so many years it only seems natural. It is like mandatory release of wild steelhead - at first it hurt, but now 20 years later -
I wouldn't dream of bonking one.
The stability issue that Topher refers to with singles is a concern. I am a great fan of GP-type flies. The problem with the traditional shell-back GP is its tendancy to roll over - even in moderate flows - a problem that does not exist with a double hook version. To compensate, my GP's employ a wing design that keeps the bulk of the material on top of the fly. I use clumps of marabou tied in two tying stations, 1/3 of the way up and at the head. This combined with the hook creates an exceptionally stable fly. You can see the flies in the Salmon Steelhead Fly Archives, scroll way down to "Tyler's Tubes"
Tight lines - tyler.
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