I have no concerns about the 9485 with cuben. It's quite pleasant to use. The strength of the bond is pretty strong as soon as you put the pieces together, and I think of the stuff more as a slightly structured adhesive, rather than tape. There's no carrier/backing like conventional tapes, so it's like putting down a perfectly consistent layer of just adhesive. If you peel the cuben apart, the adhesive randomly sticks to both surfaces, like bubble gum on the bottom of your shoe.
I'm not sure what it'd take for 9485 to fail in the field. I can say that after testing cuben bonds with 9485 to failure, there's not many field scenarios where a properly constructed cuben item is going to have problems at a seam.