craysea:Hi there Dan I'm in New Zealand so you wouldn't be the one having to rescue
me from myself. .........
Hmmm, he wouldn't but I might have to. If you're not worried about having to replace cylinders, then you might want to consider buying larger ones so that you don't feel the need to suck them dry (unless, I guess, you are already diving 123cf Fabers).
Out of interest, where in New Zealand are you? Too many New Zealand Cray Divers think they are fine pushing air limits until one day they aren't fine at all.
Best luck to you. I just hope I'm not there the day something goes wrong.
Oh, and I would definately agree that freediving after a dive is not a very sensible plan.
As you suggest, go freediving first.