Rodney

I doubt that you would be able to get by using an ESC to power your servos. Most of the ESC have a limited amount of current they can supply to the servos (usually limited to 3 standard size servos). As to receiver battery, you will get twice the lifetime from NiCads at a slight (about 20%) increase in weight over NiMh. NiCads are also better at delivering high current peaks (most servos, especially digitals, require very high momentary current bursts with abrupt control inputs. NiCads are also much more tolerant of abuse such as overcharge. From a reliability standpoint, NiCads win at slight increase in weight per MAH required.