I think that in the average application, where the light is on for a few minutes at a time, much more useful life can be derived from the Li primary cells. I am assuming that some polarization - think of gas bubbles at the electrode - develop under high current discharge, as occurs in C-Zn and other primary cells. This tends to add to the internal resistance, causing more internal cell heat and more polarization. When the cells are used briefly, then rested, more of their capacity can be utilized, as the bubbles re-dissolve or dissipate. Long term/steady-state use will lessen the cell's apparent capacity. This may explain why I get such a life from my 6PLs - I don't 'leave them on', unless I need them.
I am amazed at the two 6PLs I have - I don't need loads of light for an extended time - just 'search' time - in the dark. In my use, I don't doubt that I get a lot more life from the 123s - but I also know that were I to leave one on, in my front pocket, for example, it wouldn't take long to notice the 'warmth'. That usually is coincident with the "Hey, your pocket's glowing!" remark. I know they won't put out 80L for any 11 or 12 hr - but, in my use, I'll likely get 11 hr of 'use' per set of cells, but it will be over months.
I would say that SF's advertising is on the edge of being misleading by not indicating how long they will run near full brightness. I like their products, however, even if my sampling is one 6PL and one 6P with a P60L.
Stainz