Well it has been about 7 months since i visited this site, but i too had to order one of these UCD 46's...I have had my Flip on the work bench for nearly 8 months debating on some of the things discussed on this thread....check out the pic of bench...the main reason I haven't finished that Flip is I hate torque rods, that is the elevator using one servo for each half via torque rod, so i ordered an extra servo, nice hanger 9 servo wheel, all the other stuff and had all intentions to mount rudder servo in cockpit (pull-pull) and use 2 servos for each elevator...just haven't had the time to complete this....Since then they came out with this UCD 46 with out the torque rod set-up and i liked that, so it is on back-order...late july as of today...I have both the saito 72 and os 50 both new in box, couldn't determine which one for flip so ordered both, all carbon fiber rods, ball bearing control arms, aluminum servo arms, nearly the best of everything you can buy as you can see in photo, now from what i read here there is so much talk about this and that as far as engine size, balance issues, etc.. this one might just sit on the bench for several months, lol...no i am going with the saito 72 this is the 2nd one i have, also have the 180...and if you want to know why, i don't know of another engine that you can put 3 fingers on the spinner and give a quick back flip and it will start 99% of the time first try, i have been flying these models for 25 years and the saito is a nice motor, so is os and the ys....anyone flying it already with the 72, please let me know, very curious but i think it is the ticket...also 30% heli fuel is the only way to go with the saito's.....again i sorry this is so long of a post