I don't know too much about this, but between easy and the caa it has been scientifically proven that 6on3off is a fatiguing roster pattern. When we had the chance to vote 5/2/5/4 the feeling seemed to be that we couldn't go back to 6/3 becasue of the findings of the study.
Hard to see how the caa would allow flybe a 6/3 roster after that.
5/2/5/4 is just fantastic.