I've got a student right now who brought a NextStar with an OS46AX on it. He set it up according to the instructions and even had the servo-to-surface rigging connected perfectly. The airplane flies really good and is one of the best trainers I've had the pleasure to fly with a newbie.

It always amazes me when people condemn particular models that are in general use and that are flying well for large numbers of flyers. I've seen a number of NextStars and yet to see one that was giving the owner problems with anything other that engines some of those guys used.

As for the correct CG for any airplane, learn to use something like geistware.com and bypass the generally worthless sound byte wisdom. Heck, learn how often the mfg hasn't a clue.