I've been experimenting with spliced bridges and here's what I've learned so far...
10mm Beeline is not adequate, the core is polyester, not Vectran like the 8mm. Seems stupid, but that's how they chose to do it.
Currently I'm using 16 strand hollow braid technora from Atlantic braids spliced using the Samason eye-eye instructions. WLL should be in the neighborhood of 600#. It's really strong stuff, polyurethane coated too. I stitched the cover from 10mm beeline over it to make it ride smoother.
My ultimate plan though, is two separate spliced bridges of 6mm vectran with a single cover over both.
I'm really happy with the technora but it just looks small. It's hard to be absolutely confident when you look down and see that little, less than half inch diameter cord as your most crucial, un-backed up link to your lifeline.
...plus, I just think vectran is really cool stuff.