From one novice to another ....

The reason the UCD3D flies slow is that it is a 3D plane. By definition, 3d means that you are performing manouvers with the wings "stalled". 3D means that you give up the use of the lift characteristics of the wing so that the only forces exerted on the plane are thrust, torque, gravity, and drag. Giving up lift only happens easily at low speed.

Thus, the UCD3D is best flown slow.

No doubt that the plane flies well at speed as well, but that is not it's intended use.

If you are asking whether you are ready for the plane, well, there is only one way to find out. As for whether you can do 3d, well, give yourself some altitude, and try! Just b aware that the control surfaces of 3D planes are designed to be effective in the prop-wash of the engine. Thus, they are all close to the fuse, and over-sized. They work not by changing the aerodynamics of the wing, but by deflecting the surface in the airflow of the propeller. Thus, using them at full rates when at speed will potentially damage the plane. Further, the surfaces are so big that they exert strong forces on all the control rods and servos, making them more prone to flutter, etc. They are designed to be used at slow speeds, keep the plane slow.

gus