For sure I've missed something in a post that led me down the wrong road more than once. I guess we can get a little chuckle out of the mix ups and the mind reading then get back to the conversation.
Paul, I used poly yarn on some of the brook trout flies, and hi-viz on the others. Gonzo uses both, I believe; check his book for some patterns and materials. (And where is that fellow; oh, it's skiing season--he's probly AWOL till spring). Poly yarn floats pretty well, but I found I still needed a bit of Mucilin to keep the flies floating when I tried them. The little streams I was fishing didn't always lend themselves to a lot of false casting, and I was often roll casting or tension casting. Both real dry fly drowners. At first the synthetic winged flies were sinking too frequently, and I started to think Gonzo was full of beans when he said he prefers synthetic wings for brook trout fishing. But he's never led me wrong before, and I found out (perhaps after asking him, if not by trial and error) that with a bit of Mucilin paste rubbed in to the wing and body they stayed up forever. Spence, EP fibers may not need Mucilin--I'm glad you mentioned them, and I'm interested in trying them. I think they are softer and finer than either Poly yarn or hi-vis, and may give a more CDC like texture to a wing. (And I'm always happy to build up my tying materials. Now if I can just find someone to will them to they'll have plenty to tie with and even pass on themselves.)
I generally like CDC after fighting with it enough to have some tying techniques that work for me. At this point I should confess that I don't tie my CDC caddis the way Matt does his. I use a method that someone at Tulpehocken Creek Outfitters told me about years ago. I'll paste it in below. Admittedly it sounds very complicated but like most tying techniques, once you get it, it's not so hard. Now, Matt's flies do look nicer than mine (no surprise) but mine fish well enough for me, and I use almost every fiber on every feather, even saving the scrap tips for emerger wings, etc. I'm part Scottish.
Caddis directions: If you wish, tie in a short sparse antron or z-lon shuck. Dub a thin cigar shaped body with an appropriate color for the abdomen. Dub the thorax another color if it differs from the abdomen in the real bug. Leave an eye length or two of the hook bare just behind the eye for tying in the CDC. Select three or four CDC feathers with a majority of barbs longer than the hook length, hold each by the end/tip and stroke down the feather, pulling the fibers out perpendicular to the shaft, then stack them on top of each other, keeping the curves of the feathers the same so they will nest right on top of each other. Then holding the feather ends/tips with left thumb and forefinger, strip off fibers on one side with the right thumb and forefinger. Next find a way to turn the feathers over in your left hand, keeping them stacked and lined up. (Holding the stripped fibers between thumb and index finger, I make a Star Trek Vulcan split between the ring and index finger of my right hand, flip my left wrist over to flip over the feathers, slip the body end of the feather shaft in the split between my ring and index fingers, clamp down, and let go with my left thumb and forefinger. Then I turn my left hand over to regrasp the stacked feathers which are now upside down and in the same position the feather barbs were when I did the first strip.) Then, carefully raise the right thumb, making sure the stripped fibers stay down on the right forefinger with gravity’s help. Move your left hand to lay the fibers on the unstripped stack right down on the stripped fibers, fiber tips to fiber tips, fiber butts to fiber butts, with the shaft of the feathers right over the stripped butts. The better the butts line up from the stripped and unstripped barbs makes all the difference. Grasp the all the fibers with your right thumb and forefinger and strip CDC fibers off the other side of the stacked feathers. Roll the thumb and forefinger of the right hand away from the butts of the stripped fibers and grasp the butts with the left thumb and forefinger to gather them together. This takes some practice, and results in a few messes before you develop a way of doing it, but you should ideally end up with a nice bunch of CDC, with butts all together. Repeat several times to work the fibers into a “paintbrush” of CDC with all the butts together. Then pinch tie this bunch, butts forward over the eye, tying down just behind the eye with a couple of turns of thread. Keep the barbs on the top of the hook. Then lift the butts and lay down some wraps back right against the first couple of tie down wraps to bind the wing in, tightly sandwiching the CDC fibers between the initial wraps over them and the next ones under coming back. Next, whip finish under the wing butt fibers just behind the eye and trim the butts to expose the hook eye. Cut carefully to avoid cutting the thread. A tiny drop of superglue on the butts makes the fly bombproof, though I sometimes omit it. Then angle your scissors to cut the CDC tips forming the end of the wing at a slant, to imitate a caddis wing shape, cutting the wing about even with the end of the shuck, if you have one, but in any case leaving the wing a bit longer than the hook.
OK if you've gotten this far, you'll probably be ready to agree with some of my fishing buddies that I'm a little crazy. Can't contradict them.
"He spread them a yard and a half. 'And every one that got away is this big.'"
--Fred Chappell