Are you guys doing a Deep Dive on Carbon Monoxide Rebreathers. Would be good current topic to get an understanding of what the big teams are doing.
Given CO is toxic/lethal, my take (guess) its a measurement tool in training to see how different Altitude training impacts, to see what works best?
Would love to know from curiosity point of view. I have scuba dived with rebreathers but this last thing I want is contaminated air. 
Hugh