Great job with your LT-40. After 44 years of RC, it is my favorite trainer, and I have flown them all going back to Falcon 56 and Sr. Falcons.

The LT-40 as initially set-up works well as a primary trainer, but it can take you further with changes in the set-up. After you start to get bored with a loop or two and maybe a roll thrown in, you can move the CG to the rear of the recommended set-up and increase the control throws. Now spins and snap rolls will be possible. Of course even with the initial trim setup, inverted flight and even outside loops can be done with the Kadet. Just slowly work up to it. I would also drop the control mixing. You need to learn to use the rudder, and if flying inverted, you use opposite rudder with the aileron to coordinate a turn.