I run a hobby shop... I have sold over 200 of these since they came out. I have done many demos as well.

Make sure you have a fresh battery when starting. After plugging it in, there is a pause for the bind, make sure the heli is on a flat surface before it initializes. you will need to trim then and yes, just like the big ones with (cx2-cx3, Blade 400) when the flight time/battery use is increased, you lose the tail. You dont see it as much until the end of the flight or battery life with the big ones, but as you increase power it will yaw on its own.

My true feelings on this heli: IT SPOILS YOU. If you are struggling with this effect, DONT FLY THE BIG ONES You constantly have to fly a heli. Letting go of the sticks with the MCX (because it is so stable) will rarely happen with ANY heli that is bigger

I love this Heli and hope this helps. It truly is a great flying heli.

Sorry one more thing.. after the first minute you should have it trimmed. Dont continually trim the heli, as in your comment, you will have to trim it again after a new battery. Just fly with the yaw effect and know that when it starts, the battery is coming to its end.