Which way up?  CDC vs Deer Hair?   Roy Christie style vs Bob Wyatt style? Grip hook vs Hanak?  Tail breather vs none? I am leaning towards the reverse fly, which puts the tippet below the surface, and I like the CDC for its delicacy and movement. The Hanak hook has a wider gape, which I like. The hackle on the CDC fly should help float it, but I am thinking I could go with more sparse and longer hackle.  There are worse ways to occupy an evening…..