Duelund/distributors are offering the copper cotton oil and tinned stranded copper for great prices right now. I haven't tried the tinned, but I do have a bunch of the copper/cotton/oil and do love working with it. However, I have not been able to use it in part of the circuit I could directly compare it against other wire.
Currently I have my input wiring from RCA's to the selector switch wired with one input being bare 26 awg OCC5N silver (Parts Connexion) with 24 gauge clear PTFE, and the other input being the stock wiring. Great! Also, there was no way I was going to slide the 26 gauge teflon over that thin of silver wire within this millennium, so I opted to use 24 awg PTFE.
It's interesting to read about what tinning, oil, and other dielectrics do for the performance and sound of whatever wire you're using in audible parts of the circuit.
How's the tinned wire treating you?
-T