Im a new mCPX owner...but have read a lot on it and have flown it probably close to a hundred times already myself in the past 3 or 4 weeks that I have owned it.

What I hear on the grapevine is that the tailboom on a stock one is just too short (considering you have a V1...think they made it longer in the V2 but cant be sure about that).

Most people are making their own booms from a solid carbon fiber rod and extending it by an inch or two, you should read up on this and not take my word for it.

By using a longer boom and also a larger diameter tail rotor, its supposed to solve the tail blowout problem people speak of.

Also...if you have TOO MUCH pitch in either direction, it will cause tail blow out.  This I can say that I have tested as I have a DX7 and I had played around with pitch and throttle curves.  The tail will blow out more...the more you increase the pitch.

From the factory, my heli had way more negative pitch than positive.  But since I have mine bound to a DX7, I was able to go in and adjust the pitch % rather than adjusting the linkages like you did.  In your case however, you have no other choice as there is no way to adjust pitch on the DX4e.</p>