I am a big fan of the shrinking disc. I think it's much easier to control than heating with a torch. All you need to do is apply the disc for a shorter period of time and with less pressure, if you're worried about over-shrinking. I have found that working with the shrinking disc is actually a little slower, but surer and more easily correctable. You can always make fine adjustments with hammer and dolly as well. At any rate, I've had a lot of success in removing oil canning and related problems with the disc.
