I have seen them advertised but to date I haven't tried one myself or seen any at the field, they look like a good way to go but ?????? As to the 20% less flight time with 6v over the 4.8?? I have seen it measured with insterments in magazines but in real life I haven't ever noticed it. I run both 4.8 and 6 volts of the same size packs. From lab to field there must be a lot of other factors that figure into the draw difference??