RE: lipo transmitter batt
I've installed the Hobby King LiPo's on MANY JR radios without any problems...
However a friend installed one on his Futaba and fairly quickly had problems because of the higher voltage. He had to get his transmitter serviced to fix the problem and was told that the Funtaba's could not tolerate the higher voltages.
The JR's seem to handle the higher voltage w/o any problems what-so-ever and I've been using LiPo's since they first became available a few years ago.
It's nice to be able to quick charge your TX in one hour or less, and having it work practically non-stop all weekend.
As jeffie8696 mentioned, you should NEVER charge the LiPo pack with the standard charger. It behooves you to install a plug to remind you not to use the port if you go with LiPos.
I don't know about Hitec TX's though...