I have a T-Rex and have helped set up 3 more.
It does behave very well. Like all helicopters, setup is crucial. We paid attention to each and every joint, making sure that the ball links were friction free, correcting slop where it was evident, and setting all servo throws to give desired response. I have moved from being a hover-only pilot with my FP micro to FFF with the T-Rex. It does behave very well, and if you DO put it in the dirt, replacement parts are very affordable. My first crash was something like $11 (blades and a feathering shaft)
Now, I AM also looking at the CCPM conversion, but this is not driven be poor behavior with what I have now, but more because it has a lot of bling-factor to it.