Heliko is right, the FASST 2.4 GHz is incompatible with the 3-in-1. I too am a noob and I bought the 6EX 2.4 and found this out the hard way; I decided to keep it and to go completely separates using a GY401 gyro and I have just finished modding Axe 1 (I have 2). The 401 was ony $20 more than the 240 and I figured that I will likely use it on another heli in the future. Probably like you, I was looking to move to a different transmitter so's I could program it to be less sensitive; I have done the programming but have yet to fully balance and test Axe 1. You could buy the 6EX 72MHz version and stick with the standard Axe setup but gain the ability to program the transmitter.

I ordered a GWS Futaba [:::] to USB cable online which should arrive any day now; I'm planning to hook that up to the FMS simulator to get some practice where the only thing I need to do after a crash is press 'I'