I had to replace the inner shaft with a metal one too. It's one of the recommended upgrades on the CX, along with heat sinks for the motors.

One thing I wonder about on E-Flite helis (and I'm sure some other brands that hobby shops regularly carry) is if they are deliberatly designed to be just unstable enough and also breakable enough to be a guaranteed revenue stream for the hobby shops and manufactures. I know the local hobby shop I used to go to lied their tails off to me about how easy the CP was to fly. They said it was only slightly harder to fly than the CX. Yeah, RIGHT! I also found out they were charging as much as 10% over full list price for a lot of the replacement parts I needed. Needles to say, I don't deal with them anymore. I do have a really good hobby shop in the area (probably the best I've ever seen) but they are over 20 miles away from me and I can't always get the time to go there. Look on the internet. Some great deals on parts there. For example, I've gotten replacement blades for my CP from Helidirect for half what E-Flite and the HS charges for them.

One thing I've had to learn from flying Helis is bargain shopping. Otherwise, I'd be bankrupt by now!