Just a note on this: I have been playing around with the yarn indicator secured Dorsey-style to the leader using the dental band. Have been using polypropylene yarn that I got from AliExpress.
I was testing with a pint glass of water and I made up a big fluffy indicator and hung a small tungsten beadhead nymph off the indicator. It immediately sunk like a stone. I said to myself, what a load of rubbish.
Then I remembered someone saying that using floatant on the yarn made a big difference. I re-fluffed up the yarn , then applied some Gink and brushed it right through the fibres. Dropped in the water and the yarn was floating like a cork. Came back hours later and was still suspending the nymph perfectly.
Later on I tried the same indicator with that small nymph plus a size 8 double tungsten bead nymph with a wire body and uv resin over the wire -this nymph sinks insanely fast. The indicator sat a bit lower in the water but held it up all the same.
Another one I have been playing around with is using booby cord pieces, about an inch long. Attached the same way to the leader using the dental band. I didn't secure to the middle of the cord, instead it is secured near one end.
The great thing about them is that when the nymph is suspended normally, they lie flat on the surface, like a cigarette butt floating downstream. However, I was able to simulate a subtle take by dropping in another nymph on a length of tippet secured to the bend of the suspended nymph.
Before the cord will go down altogether, the secured end will sink and the unsecured end will actually raise up (like the Titanic sinking!). I think this might be a good way of detecting subtle takes that would be missed by other types of indicator