Hmm...

While there could be something wrong with your setup, you must remember that heli's do NOT just sit there in a hover. I've got a little bit of time in full scale heli's and the simulator is quite close in the amount of effort required to hover. My Blade CP is more difficult to hover than either full scale or the sim.

My flight instructor on the full scale heli described hovering like this; "it's like trying to stand on a basketball" and he was right. A stable hover requires constant minor corrections of all controls to accomplish. Getting it trimmed right will help, but it won't make it just "go up and hover"...