Most of the time it seems when I need to remove a frozen bearing from a shaft, it's in a tight spot or buried in the machine. So an acetylene torch is often the fastest way to get things apart. A torch is messy, potentially dangerous, and inelegant, but effective. The same has been said about me, so I guess I'm a good match for a torch.
But there are times when a bearing is out in the open and accessible, and I'm glad to use a die grinder with a cut-off wheel to quickly and surgically remove the bearing. Today I was in a situation where the bearing was on the end of a shaft and there was plenty of room around it, so I grabbed my die grinder. I made two cuts 180 degrees apart to split the outer race, then carefully cut through the inner race without marring the shaft. It took a total of 5 minutes, and avoided the flames, sparks, soot and heat that would have been part of torching the bearing.
It's not always possible to use an air-powered die grinder and cut-off wheel to dissect bearings, but when circumstances permit, it's a quick, clean way to get the job done.