[Zeke]

It will destroy the wooden bat, that's for sure. So, if you want to sacrifice a bat to save your paint (if possible), that's the main reason I see. But if you want to get the job done quickly, use the metal bat.

The thing is, if the sharp edge of the inside of the wheel arch can't slip up on the metal as it's being folded, you stand a good chance of kinking the outside of the arch. Now, you will be painting for sure. You see, the tire rubber tends to hold the bat in one place not allowing it to "follow" the metal as it's bending upward. Using the bat at an angle helps with this. I still like an old pipe, myself.

The rig that attaches to the axle studs with the wheel off the car looks to be the best deal going. However, I've never had the oportunity to use one.