I have launched my Spirit Elite off a highstart and a winch with no problems, including pedal to the metal zoom launches off the winch...it has basically the same wing config as a regular spirit. A guy I fly with has also launched his Spirit off of the same winch and the same highstart with no problems. I don't know the actual diameter of the rubber on the highstart but it puts the plane up there really fast and really high! The high start has often been described as "excessive" and it's main use it putting up unlimited ships.

I wouldn't really worry about the diameter of the tubing and all of that...if you think it's going to give too much "oomph" for your spirit just don't pull it back as far. I think you'll be pretty impressed with how strong the wing is though.

Good Luck!
Averen