Well, I did (see the link JanVanHove posted)...
I used it as an F-string (since I detune my 5string 1 step to Bb, Eb, Ab, Db en Gb). It sounds great when using some compression. Without compression it sound more muddy and it doesn't have the same volume as the other strings! But the string sounds great comparred to the other strings (very nice balance).
It is usable, but you should have an very open mind...it's nothing like the rest of the strings!