yes, the wings are very strong as are most sig wings (i love sig kits... im partial i no) BUT! its also VERY thickwhich will cause more sheer stress due to a larger crossectional area. however a .70 ish engine should be well in the means of the plane. if you are worried about it laminate the main spars with light CF cloth. ive never used a GMS so i cant comment on it, but ive used several OS engines and am not blown away by them. yea, they start with a cylinder full of sand, but who cares? they cant turn the prop. (ive started using magnums since they seem to be built much better, though they dont greatly outpower the OS's they are cheaper :-D (my spitfire is running a mag 1.10 the engine cost less than that LA 46 :-D