Guys,
I tried the 6S (Two 3S in series 5,000mAH) Li-Poly and my 5S (5-Cell, Turnigy 4,000mAH) Lithium Polymer.
The 6S really didn't provide any additional performance and perhaps slightly a little more airspeed. It did have a greater climb rate, however.
The 5S using the APC 13 X 8 "E" propeller is the best for this Thrust-50 power system and airplane model frame. There is just no need for additional power required.
I was thrilled to have an opportunity to fly the LT-40 Kadet before heading to work this morning and it was a total success.
The newer 3-inch diameter FOAM wheels on the Main Gear were terrific and I didn't see any bounce at all and performed a few Touch & Goes and the model handled like a baby doll.
I am having lots of fun with this model.