What nonsense you are talking TogaLock. Most guys are not getting defensive on this trading about FR "secrets", they are asking you how you noticed that they had single pack operations!
So I'll ask again, for whatever reason HOW did you notice "single" pack operations on the FR flight you were on.
BTW on the 737 NG if you are @ FL400 and you get 1 pack trip off and unable to reconnect you WILL need to descent, cos 1 pack can't cope to maintain the pressure differential.