I built a .60 Uproar this past summer. It wasn't my second plane but it could have been my trainer with the right instructor and the throws on low rates. I powered mine with a .61 Thunder Tiger. I extended the rudder by 1.5 inches and reversed the radio hatch so I could add a canopy( the .60 size doesn't come with a canopy). I also upgraded the main landing gear as well. And added sheeting to the outside wing tip and the inner wing section to gain strength and a better place for the covering to stick to. With my throws turned up a bit and a bigger engine such as a .91 size it would be a monster. With a .61 it is a solid fun plane to fly. Below is mine with my beautiful daughter holding it up.

P.S. I have seen the .90 size Uproar fly and it is a great flyer. One of our club members also has one here in McMinnville.