sounds good to me, C140 is too big and expensive for me and C50 is too small to fly easily (maybe have not flown mine yet!) I guess 7.5 lbs would be okay, my synergy weighs 7lb 2oz and goes up like a rocket on an OS91FX and mini pipe, prop hangs at 1/3 throttle, high alpha knife edge at 3 clicks above idle, it cost £350. My C50 cost £212 with covering, glue and carbon accessories and I still had to build and cover it. Wonder what the C90 will cost? Best thing about building yourself is being able to make sure it is glued up properly but I have to say the synergy was glued up just fine.