In reply to UKC Articles:
This is very similar to the way I do it.
This video shows almost exactly how I do it and teach it:
It's important to consider the bigger picture, yes your hair is more likely to get caught if you haven't tied it away/kept it out of the way, but your prussik is much more likely to be effective, which is ultimately more important. Keeping my hair out of the abseil device is in my control, being knocked out by a random falling rock isn't.
As for using slings, keep them snug and you've nothing to worry about. it'd be nice to be able to use the rope, but hey, you'll be throwing down the cliff! So what else do you use, unles you're carrying spare lengths of rope around?
Finally, if you haven't already tried it, do so. Having the ab device above you puts your centre of gravity nicely low, the whole ab feels a lot more secure and comfortable in my opinion.