Ok good you know the CG point. And yes your guess on motor weight affecting the difference is plausable. Also where you may have added to your off CG was in having to shorten the motor stick. I saw you said you did so because of the motor to esc connection.

There are ways around that. Maybe it would be wise to have one of your club mates give your bird a once over before you attempt to fly it, would really be good if the one who has one like it looks at it. He could give you tips on it, and maybe make some suggestions as to whether it will fly correctly in the altered state you have it in.......before you maiden it and end up with a mess on your hands.

I know we all get excited with a new bird, but often slowing down and making sure all is right can save you a lot of misery and dollars in the long run.

Heck I have these birds and a few others all waiting to maiden this year, dang crappy weather, but I've learned that it's better not to rush things.