I have the Goldberg Extra 330 with the BCMA 40cc gas engine. Perfect combination, in my opinion. Use good, strong servos with large, heavy duty control horns if you want 3D performance. I put the rudder servo in the tail and the battery sits at the former just aft of the wing. I have flown the CG Yak and I liked it a lot. The owner of that one did not have it set up for 3D, so I don't know how stable it would be in those maneuvers compared to the Extra. But, I will tell you that on 3D rates in the Extra, when I pull full up, it just stops and points up, exactly like I want it to. I find it to be very stable. It does not glide well at all, but I doubt any of the three would considering what their designed to do. I think the Extra is a fine choice for 3D and sport flying.

I was flying it the other day, having a blast, 3D'ing better than any plane I've ever flown, and then the engine suddenly quit while I was only about 50 feet in the air, pointed straight up. I ended up landing hard in the field and breaking the gear off. When I tried to bend the gear back into shape, it broke! So, I ordered new gear. That's one problem with this plane is the landing gear bends pretty easy. I had bent it several times before that, so that's probably why it broke this time.

I plan to rebuild the landing gear plate without the aluminum pieces and use 1/4" plywood with balsa triangle reinforcements. I will then mount the gear with four 1/4-20 nylon bolts. I like that set-up because the bolts will shear off in the event of a crash or hard landing and save the rest of the plane. Then, you just replace the bolts and fly again...

Let me know how things go for you.

-Pat