Fly the UCD. If you can handle a Goldberg Cub, then you are ready. Just keep the rates down to where you feel comfortable. I have a Goldberg Cub and it is much harder to fly correctly than my Extra and Cap. Just be sure you have strong enough servos and good tight linkages because of the large surfaces. It will flutter and destroy itself with any transgression of sloppy setup or weak standard servos. I have seen it with my own eyes.