Jeremy,
This a great posting. I have to add another bead to the mix..... Crystal!
I fish most of the times in the parks and the Current River. But I learned a lot by fishing out in the western states that by adding a Crystal bead to most any small fly or midge pattern, you increase your bite ratio. So I have used this technique back here in the Midwest with lots of success.
Over the last 7 years of tying midges, I have added Crystal beads to 75% of my flies. The size range is from 16 to 24. I add to them to Pheasant Tails, Hare's Ear, WD40s, RS2, Buckskins, Zebra, Scuds, and the list goes on and on.
As for weighted bead, I used the copper and black on some Zebra patterns.
Later,
FFM