James35

iTrader: (1)

It's a different manufacturing method of creating magnets in a desired shape. The nickel coating keeps the magnet together better. Generally sintered rotors produce more magnetic strength than a bonded rotor, and have slightly better resistance to losing magnetic strength when exposed to heat. (Although bonded rotors are still excellent, since they both use Neodymium magnets instead of Ceramic)
Usually the only difference is slow speeds can be choppy/inacurate without the sensor. But recent speed controllers are getting better.
It basically lets the speed controller know the exact position of the rotor, so the speed controller knows exactly when to fire it's next burst of power to the appropriate magnet coil.
It shouldn't be hotter nor create break fade. You may have a problem. What ESC do you have, and what motor are you running?
Kv is RPM's per volt with no load. However, it's only half of what determines power of a motor. Torque is the other half.

Horsepower (Watts) = RPM x Torque
746 Watts = 1 electric horsepower

Watts of power that a motor generates at 7.2V is the proper way to compare any motor. The reason you see manufacturers using Kv ratings, is because Kv ratings is easy to obtain. They are being lazy and not hooking the motor up to a Dyno with a controlled load to determine Watts of power.

Don't get caught up into using Kv ratings.
This is the number of turns (wire loops in the electromagnet coil) used in the motor. The less the number of turns, the more electricity will flow. This causes the electromagnet coil to generate a stronger field, but at the expense of pulling more power from the battery.