I agree that spectra is very strong and abrasion resistant material - however, I think gemini cord would be more appropriate for this use. Gemini cord is very thin, but very strong (kevlar and spectra combination), and is pretty stiff - which I think would allow for a more fluid torque around the point of attachment than the more floppy spectra sling. I think gemini cord also shows superior edge cut protection/resistance so you wouldn't have to worry so much about angle iron etc...
just my 02cents
sum1