My UCD 60 had the widest flight envelope of any model I've ever owned. Its extreme lightness allowed it to basically stop and mid-air and not stall right away. I could "walk it down the runway", IOW, walk alongside of it while keeping the nose up, about halfway between a hover and flying a straight line. An accomplished 3D pilot can do amazing things with one. Yet, my young grandson had no trouble flying it during his formative period (fresh off the buddy box/trainer).

But there is no free lunch. The UCD airframes are rather fragile, and will not take much abuse, such as hard landings, etc. That is not to say they are short-lived; I've seen one that was flown until it was basically falling apart, but it took three years of being flown almost every week-end to get there. Just keep the landings gentle...

So, if you are comfortable and COMPETENT with a trainer, a UCD will not throw you any curves. Just be aware that it will do things you might not be ready for. The way to avoid that is to keep the control throws at or below the minimum listed in the manual. As you become comfortable with the UCD, gradually increase the throws to your taste.

And don't overpower it. A .91 four stroke or .61 two-stroke is plenty for this airplane. Just be aware that an inverted installation will require some sort of pump or regulator with most engines, due to the tank being well above the carburetor. Contrary to some opinions, a side-mounted engine is absolutely no problem on this airplane. Mine had a side-mounted YS 91 FZ, which was WAY more power than needed for normal flying.

The UCD has been a very popular model; IIRC, the only model that has had a longer-running thread here on RCU during the height of its popularity has been the EF Yak, and possibly the H9 Funtana 90. Dig up that old UCD thread; it will keep you busy reading for hours...