I would vote to leave it stock as well. Mine was the best flying 3channel model I've ever had, and I've had a few. Quite happily do good barrel rolls and inverted flight at very low airspeed. I only sold it to make more space in the workshop and wish I hadn't. Still got the plan though...

As an aside, at a fly-in last year, there was a bloke doing loops and rolls at *very* low altitude, ie fun-fly under 40ft altitude, with a Kadet Senior. 78" wing, rudder/elevator, no ailerons, powered by an LA40. Beautiful to watch.