Greetings BPL friends,
I've used the MYO XP for 3 years with Alkalines, Rechargeables and Lithiums. I LOVE this light, and have had no negative issues with it (NONE!). That is until it just plain stopped working about a year ago. I called Petzl, customer service said "send it up" and within the week a brand spankin' new one arrived via mail. Turns out there was/is a recall of some sort. I mention this to reflect a MOST EXCELLENT PETZL Customer Service experience!
However, while on one of the other outdoor gear websites discovered a new model, an update of the MYO XP. The MYO RXP. Was surprised and saddened to find that it does not come up at all on the BPL "search". If you like this headlamp, look into the updated version. I find the improvements highly desireable.
I am getting one !