Hello,
(sorry for english, but trust me, better than my german = : D)
we, my son and me, built one each. My son's is 990g, while mine is 940g. Both nitro powered.
First point would be weight is not an issue! It affects speed, sink rate and climb speed. Obviously for combat, the lighter the better for climbing and maneuvering, but heavier could help for speed.
As a side note weight affect flight performances as quicker means higher Reynolds number and better airfoil behaviour.
Engine offset is an issue. Mine is set at 0° and it feel a lot the torque, especially at full throttle and low speed, e.g. launch, top of loopings etc.
My son's is set with 2° to the right and it flies really straighter than mine.
Strange is that we set both as per plan, on CoG and longitudinal dihedral, and mine flew just as expected (except torque issue), while my son's was unflyable at test flight (I did them both), being way too much sensitive on flight controls.
We set my son's at a more forward CoG and it flew well from then on. Probably he built his one with less longitudinal dihedral and the static margin results lower.
Those where posted already, but I post a couple of video again to show how they flies.
My son's:
Best regards,
Ric