Test graphs seem to show an acceptable level of Co2 post scrubber (the point of measurement).
Now the question is "whats the level of CO2 in the DIVER from the elevated WOB thats typical on CCR's" (dont forget oc is not really passive, once you crack the valve the gas is slightly pressured). Personally I 'suspect' its slightly higher, but its a bugger to measure.
Anyway, its all bollocks. I refer you to the previous statement about the real world where most ccr divers dive mix all the time. The Air dil brigade will always exist (as will OC deep air) but its so cheap to dive trimix on a ccr that even the tightest of jocks do it <pointed look in a certain direction>. Dont forget that ccr's do require more monitoring/vigilance than OC, so a low narc level is desirable anyway.
ps. Yak.