I have two Cubs, a 1/4 scale Balsa USA and a Goldberg. I agree with the sugestion of toeing in the landing gear as viewed from above. It works, with and without varying throttle control, and I fly off pavement. You can also add a heading hold gyro and switch it off as you leave the ground. My buddy couldn't get his Great Planes Cub to behave, so he added the gyro and it solved the problem. Make sure you are able to control it from your Tx or you will encounter some other problems.

Bob