You made a good choice going with the PT-40. I built one 5 years ago, and the first time it was flown the instructor had me make a small adjustment to the elevator and that was IT! I built mine with the 'A' wing and even with the dihedral it loops, rolls, does split S's. Even got a half way decent hammerhead out of it.
One time while I was still buddy-boxed, the instructor took over for a few seconds and had the plane flying in a circle, banked slighty to the left. It made a couple of laps and the instructor said "Those are pretty good circles. Now try something else."
I said "I thought you were flying it?"
"Nope. You've been flying it."
I said" Uuuuhhhh.... no, I haven't."
"Pretty stable ship you built there."
I use rubber bands on mine, too. At the end of the flying session, just put them in a plastic sandwich bag filled with cornstarch. It dries out the rubber bands quite nicely.
Mine is bright yellow on top of the wings, elevators, and the rudder. as well as the top half of the fuselage. The bottom of the wings, elevators, and fuselage are bright red. The plane is known as "The Flying Hot Dog" aka. "The Winged Wienie."
Enjoy it!!