Fenix L2P is now in the queue of lights to buy.
This said, I like in a special way the one AA cell Lux lights. May be some of you are of the right age to remember keychain lights with "122" bulb and one zinc-carbon cell. Definetively, we have an improvement.
Also, I realize that having full regulation on one AA cell is difficult. The voltage is too low, so great care must be given to all details, from the size of the tracks on the PCB, the saturation of the MOSFET, the sync rectifier if any, the quality of all contacts and soldering joints. But, above all, it is the size of the necessary inductor that drive me crazy!
To have the necessary "slack" to implement full regulation with 1.2 Volt, I got to use an inductor that is the same size of the head of the L1P. Partly because of the size of the ferrite core, that can never get into magnetic saturation; but mainly due to the diameter of the copper used in the winding to reduce the losses.
A solution would be to increase the frequency of the oscillator, but other problems (losses) arises there.
So, small, cheap and fully regulated doesn't apply to one cell Lux lights.
May be in the future some company will make a commercial "resonant LED Driver" to use with one cell and a Luxeon. Personally, I don't think it is worth the hassle to design and realize one now.
This is what, very likely, has been the tought of the L1P designer... just add another cell! Make life easier.
I had the best 2AA regulated Lux light three years ago, and still works fine... it is the Arc-LSHP with the 2AA tube. Then I have MM with sandwiches. Sooner or later, I will also have a L2P. But this is beside the point...
I want, really want, a 1 AA fully regulated!
Anthony.