DrMike:Just saying I can get 12 hours and 2 hours is too soon - makes no sense without consideration of the variables involved. 2 hours is not too soon if for example the next dive is a deep one.
If this is directed to me, I already said, that if I am doing a deep dive or a cave dive, I will change sorb accordingly, I didn't say this is a hard and fast rule.
I don't think we will see an accurate gauge on scrubber life other than your own experience within your own dive conditions. If I am wrong, too many people will take the gauge as gospel. I can see it now, "but the gauge said he still had XX hours of life" and the dead diver didn't think about the head ache he was experiencing or the other symptoms as he passed out and died.
Dennis
Edit to add:
OK, so it wasn't on this list that I defined my routine. You should always consider the dive you have planned and use the correct sorb for the dive, whether it is new or has hours on it. There, the obvious is stated. Sorry for any confusion.