I run 6V metal hydrides on everything. The 6V MH batteries are just as light as a 4.8V nicd pack--if not lighter.

I DO notice the speed difference in the servos.

In theory--a 6V pack is adding 25% more torque and speed.

They do run down faster than 4.8V systems--so keep an eye on them.

A MH battery does not have the gradual discharge curve that a nicd will have.

In my experience--using the cycler--when a nicd battery gets down to 6.1V or 6.0V--they will hold it and then fall off slowly untill they reach about 5.6V--then they drop quick.

A MH battery will hold it's power for a longer period of time---up front. They will hold 6.2---6.0V for a LONG time. But when they hit 5.9V--they drop like a rock. FAST!!!

Keep your eyes on those MH batteries.

I usually hit them with the field charger when they get down to 6.0V or 6.1V