I've plugged in "standard-sized" red/orange/green LEDs into the AA mag-Lite & Snap-On MiniMaglites (ensure polarity to work - it's an On/Off test) which give "acceptable" map-reading capabilities, but have yet to find a source for any "high-intensity" white LEDs.
Again - I've yet to be able to test any WHITE LEDs - of ANY flavor.
Although the high-intensity white-ones would be "preferrable" for a high-intensity type-of-thing (& that debatable w/o any testing for "room-illumination," etc.), the "other colors" (especially red, for non-diminished night-vision), will last, on one paired-set of AA alkalines, will last, for a continuously ON, for over 2 years.
Read that last again.
I have personally tested a standard RED LED panel light, & perfectly suitable for any low-light map-viewing, & that can merely be plugged directly into a standard MagLite MiniMag (AA flashlight, or an (actually "better") Snap-On AA) .... they'll last for 2 years continuous, & have yet to see any degradation for using others intermittently.
Has its possibilities ....