Interesting stuff! I havent done any rope work for years but when I was into that kinda thing I practiced crevasse rescue ascending a rope with three prussik loops and it is bloody hard work and they do tend to jam!
Ive just tried out the French Prussik and the Klemheist and neither of them are as neat or as confidence inspiring as a standard Prussik IMO! But if the BMC says theyre ok I guess they must be. As long as youre not using very thin lines I would have thought a Prussik would be fine for your Basha and its a nice clean looking hitch, in fact you might even get away with a larks head, dead simple and easy to release.
Jason