Sasqui wrote a review of Petzl Myo 5 Headlamp on December 2, 2004
So, I first purchased a MYO 3 from EMS and was luke-warm about the level of light from the LED, so I purchased the MYO 5. On high, it has a definitely useable light level for walking, even for two or three people. I tested the battery life and on 2500 Mah Ni-MH batteries, got about 30 hours on high (not bad). The nice part is that the light level is "regulated", so the intensity drops only slightly throughout the 30 hours, but then takes a complete nose-dive. For comparison, I ran the MYO 3 side-by-side with the MYO 5 on level 2 After 18 hours, the MYO 3 level had dropped well below the MYO 5. By the time the MYO 5 had died, the level of the MY0 3 was almost unusable, but it kept lit for almost 2 times longer. The fact that it is not waterproof has me concerned, I'll just have to see how it does in rain. I am happy with it.