Digital BW, The Print

I do not prefer a years lifetime metric, even in the consumer sphere, because it does not convey the uncertainty involved. (This is especially true when one sees numbers like "97 years" which imply a precision--not 96, not 98--that is truly fictional.)

But I also recognize that megalux hours or ppb-hours or the like are not going to help the consumer, as valuable as they may be for those truly interested in print preservation. 

My inclination is towards a range for each of the four important factors (heat, light, and pollutants--humidity requires something else) as star system without further qualification fails to convey what Mark said--that most name-brand products will last at least several generations under normal use conditions.    

But if we think we can couple those star ratings (for each factor, of course) to an explanation that educates the consumer as to more than just their relative meaning, then--hey--I'm OK with that. (A good portion of my career has been spent working to help consumers and others understand this sort of stuff.) 
       
Basically, I think there is little disagreement between Mark and me over this, and instead we can move on to arguing over test procedures, light sources, endpoints, meassurement protocols, and the like, where there are still many problems unsolved over which reasonable and passionate people can disagree.