I have 2 eagle 50's and I just bought 2 used 22e's of of ebay. I have yet to lose a main or tail motor even one the one that has never had heat sinks.

Be sure to do a good break in. Run the motors in 30 second bursts for most of a battery (till after the 30 seconds the motor is only warm to the touch) then move up to 45 seconds.... then a minute then still check it after a minute and a half or so. On any brushed motor until you get the brushes seated well heat is going to be an issue. If you break them in well though you can see 100 packs+ on a motor without the heat sinks.

If your flying in the summer in very hot weather (I live in Fresno CA 100+ days over and over). The heat sinks are a wise investment and you should use a thermal transfer compound when installing them. It only costs a couple of bucks for a tube at radio shack. The heat sinks from a honeybee FP will fit right on this bird if you want to add them.

If the head isn't setup right (aka been crashed and not reset properly) it will kill motors. .

I have converted one of my eagles to a totally brushless set up and I still have the brushed motors sitting in my case waiting to bail me out on the day I do kill one in my brushed bird.
If you are new to the eagle/22e read the walkera 22e "Let's Talk" forum. If you search that thread you will find almost any topic realted to these heli's covered.

Happy Flying

TeeJay