neilt6,

I run a 3 cell lipo in my CX and CX2 all the time.
The only time I burned a 4in1 is when I decided to see just how much it could take so, I ran 2 batts. back to back......it smoked about half way into the second pack.

Oddly....the CX seems to run better with a 3 cell. It hasn't "glitched" but once or twice and the tail drift isn't as bad either.

The CX2 is just flat out awesome with a 3 cell. No great "improvements" other than power and flight time.

I can say, it's been about a month or more now since I started using the 3 cell lipo in these and I haven't had any trouble other than the one time.....and seriously doubt that would have happened if I hadn't pushed it.