I got a .46 size about a year ago and flew it over the summer. This was my first 3d airplane I've flown to learn 3d on. It was great in the beggining cause it tought me to hover. I also learned everything gjeffers said the hard way but I got through it. I slapped a O.S. 91fs on it right away. Later in the year I chopped the nose down an inch and know it can mach some of the intermediate skill levels. Anyway I don't know about the 90 size but I can tell you this if you build the ucd .46 the right way and get it to hover half throttle you'll be a 3-d fly before your eyes. Garanted. and areo-fly pro you can't go wrong. the only downside I see to the ucd was that I grew out of it in one year. Know I'm ordering a WH 28% Edge 540. 15 years old 1 year flying expearance 2 years building. Hard on money but come on throw somtin' else at me![>:]