I can only draw on the experience of my wife's Evo and my TRS. The Evo brakes are less good and the bike is a bit gutless compared to my 280. She (the OH) loves the Beta and finds it "perfect". She has been a road rider for a long time but no off road. (Current bike Ducati monster, last bike CBR600RR)
The extra power of the TRS means it climbs on much less throttle compared to her smaller Evo. Beyond that they are both good trials bikes capable of far far more than either of the riders. My bike spat me off the back the first time I rode it and was a big step up from the Rev3. It took a couple of hours but the engine only revs as far as you turn the throttle and the drive stops turning the wheel if you pull the clutch in. I've got very used to it now and love it. Still scares me if you go over a big obstacle and give it too much, but that's just me - crap.