I use whoopies now, have used rings/biner on a HH Exped Asym for some time without problem, but hear that this can cause wear on the Spectra support ropes.
What if, before tying the Garda knot, you just take the Spectra, fold it in half, then run the loop thru the bottom of the rings, out the top, around and up through the bottom of the rings again and then bring it out between the two rings (just tying a Garda knot with a doubled rope instead of a single line). Finish with a slippery hitch.
This seems easy to tie, still adjusts easily and holds well. I don't know the math behind it, but it seems to reduce stress on the Spectra, doesn't seem to weaken the rope, and may solve the problem of wear on the Spectra from the rings. Anyone know if this has been done before, or any problem with it? If it works, I'll call it the Romany hitch . If it doesn't work (or does knot work), I'll untie it and throw the idea away!