Poor regulation is just one of those compromises when your input source and Vf are so close to each other even at the start with a fresh cell. Cost/convenience/packaging are the foremost considerations in a single cell light, usually. If only we had 2000mAh 18350s and 4A 17mm buck drivers...
I appreciate it, but it would be nice to build a driver more like with DrJones and texaspyro of have done. Granted, once they are done there won't be a need to do the same thing :)