If you put a lipo in your transmitter you have to:
1. Remove it to charge it
2. Watch the battery while it is charging.
3. Never let the voltage get to a certain level.
4. You need a special charger.
5. If you forget to turn off your transmitter you will ruin the battery and possibly ruin you transmitter.
6. Never store your transmitter in your trunk if it a hot day. In the summer my garage can get to 140 degrees. I have to take all my lipos out and store them in the refrig.
7. For some transmitters you need a regulator.
Why anyone wants to put up with all of that just so he has to charge it a few less times is beyond me.
Eneloops will hold 75% of their charge for three years, you can charge them with your charger and there is no chance of fire.