For serious outdoor searches, the TurboHeads rule! Vegetation and bare ground simply eats up light like you would not believe. I have a friend who is dumping his M3 standard for an M4 Turbo because the old light does not give enough illumination (with the MN 11 225 lamp) to suit him for his uses in Africa. I have an M4 Turbo and it is a very nice light for outdoors...indoors, I do not need so much light. Obviously, you cannot simply "turn down" the light...although you CAN fabricate a cover that will reduce the emitted light to a reasonable level.

If your needs are for mostly outdoor light, I think the TurboHeads are well worth the additional price. (BTW, in that pic, if the grass and fence were not there to reflect the light...maybe a dark swamp instead...you would begin to get an idea of the real potential of both lights outdoors, and neither would look nearly impressive!)