[Jack Jones]

Many are missing the point that the keyword here is backup. Any electronics added to replace the NiCad and yet store enough juice to power the RC (ETC.) during brownouts is sure to be less efficient than the NiCad.

That is, you can't get something for nothing! Instead of having a pre-charged NiCad, you use power from the main battery, which is a net loss of power available at the start of the match. You'd also gain weight!