Concerning batteries in HW.

SLA is far from obsolete in HW, whenever you need serious amperage's, you cannot beat an SLA with any type of other battery. Not Nicad, Not NiMh, not LiPo, not A123.

All the newer types of batteries, rely on setting them in parallel, to up the max output. The only advantages you have with the newer type of batteries is weight. I still have 2 heavies with SLA in them, Mantis mk2 and RCC2. I won't even consider moving these to a different type of battery, SLA is perfect for them.

I know that in vapourbots the batteries are kind of an enigma, but don't assume that because a technology is older it doesn't have advantages. Not a lot of people know that a mechanical speed controller is more powerful and less prone to failure then an electronic speed controller, because hardly anyone uses them anymore since ESC's are more energy efficient. That doesn't make mechanical speed controllers bad or unusable.

For the most bang for your buck, SLA is still a very viable option. If you are pressed for weight, NiCad, NiMh, or A123 is the way to go.