Roguerat, I don't use any goop on the mono or on thread and I never seem to have any issues.
BTW, I have been tying the comparadun just like Matt does for at least 40 years. If the thread dam is not built up enough over time I find the wing has a tendency to fall forward. The bigger the fly the more it seems to accent the problem. Also, I always felt the side profile wasn't exactly how I really wanted it, but the flies still worked great anyway.
It was only recently I discovered by mistake placing a second clump of hair in front of the initial clump. After I had tied in a clump of deer hair on a Hendrickson comparadun I realized it was way to sparse. To salvage the fly I decided to place a second clump in front of the wing. It not only worked I really liked how it made the wing stay upright (and slightly slanted back) even when I tried to push it forward. Plus, the side view to me looked much better (
my personal preference). When I tried it on the bigger patterns I decided to add a small drop of super glue to the base of the wing and then whip finish. The wing ain't going anywhere after the small drop super glue. There are probably a lot of other guys doing the exact same thing as me.
I have always used heavy gauge mono from old leader kits for tying the extended body. I posted how I do it a while ago here..
http://www.wiflyfisher.com/Hexagenia-Comparadun-Dry-Fly-Pattern.asp. I have also experimented with using wild boar hair instead of mono and posted something here...
http://flypatternsfortrout.com/2012/02/22/extended-body-comparadun-using-wild-boar-hair/. The boar hair works fine as well but I think it's pricey for a little swatch of boar hair on a card.
Although I generally use microfibetts for the tail on the really long extended body patterns I would prefer a natural material if it was durable. I have noticed microfibetts curl when in heat or sun, even inside your vest. IMO, Wood duck and other duck flank feathers look much better to me but are flimsy and not as durable.
HTH,
John