Well now! It seems you really do need to visit CPF (that's
www.Candlepowerforums.com) if you really want to delve further greater info.
That being said, I suppose a universal approach to one's gear (knife, lights, bags, gizmos, etc.) with the four (4) R's:
Ruggedness, Reliability, Right Tool and Redundancy.
Ok so you've probably zeroed in on the first two, so I suppose its now a case of Right tool and Redundancy now.
I have three lights (usually carry two though). They have their purposes.
I carry a small
LED Inova on my keychain for lighting. Its small enough to always be there just in case you need a light and bright enough for most lighting tasks. Since it provides "just enough" lighting, it's more of for task/area lighting, and serves only as back-up.
For more muscle bright-wise, my primary light is my
Streamlight Twin Task. It's a combination of the "throw" of an incandescent central bulb coupled with the efficiency of three outer LED lights. It runs on two CR123's which may not be too common though BUT do have a ten-year shelf life is unused.
Lastly, I have cheap, no name incand headlamp running on two AA's. It affords me to free my hands if needed and its cheap, hasn't failed me yet and easily accessible batteries.
Boils down to the right tool/s for the right job/s.