For the longest time my issue was the safety of Li-Ion cells and lack of UL or CE approved batteries or well recognized manufactures providing these batteries as aftermarket items for use in devices like flashlights. Ironically there seems to have been more reported "events" of battery failure in lithium primary cells than in the rechargeable Li-Ion and other similar chemistries. Personally I have so many flashlights siting around that using rechargeables in them would be a bit confusing and unnecessary since they don't get used much at all.
However recently I have taken the plunge and do use RCR123's in the few lights I do use often and carry. I use protected cells as the converters in my lights do not have a low voltage shut off. My laptops, cameras and phones all use Li-Ion batteries and I can't imagine switching to a primary cell even if it were available. For an every day use device a rechargeable battery makes a lot of sense, IMHO. For a backup or emergency device that sits until such time it is needed, I think a good, not activated, primary cell is the best choice.
