Mark- yours is busted then, mine will hold pos or neg for hours... although thats a bad idea as you know, it buggers the diaphram.

With regards Jetsam releasing these figures, we know now that they were part of Kevins multi-rebreather tests, like for like on all models, as shown at the dive show, yes predicatably the Sentinal came out top but then it is the newest model so shouldn't it also be the most efficient deisgn? (standing on the shoulders of everyone else)

Hopefully someone got a picture of it or it'll be posted here in its original file format.