Norm,
It looks like with the tied termination of your working end, you avoid having to have a wrench. Is that so?
This seems like a good back-up, but lacks the ability to rappel on your climbing system, no?
I vote HH or WR. HH can go from DdRT to SRT with no changover.
Both take you out of the Circle of Death, if the spar splits, as compared to a friction saver with DdRT,
As Nick Bonner has pointed out, a SRT system with the HH in SRT mode can be released with the rope loaded below with a second climber, which is good for an aerial rescue scenario.