I tried a side-cutter once, and I kept collapsing the sides of the cans. Without that bead around the top, the side of the can loses its rigidity and the sharp edge moves from the lid to the can itself. shrug - I've never had problems with the sharp edge of the lid, and I've found no advantage to a side-cutter. Clearly my mileage varies, and yours will, too.

I've forgotten how many mechanical can openers we've got. At least two in the kitchen (one on each side so I don't have to chase it), one on the camping box, one in the van. Plus the venerable P-38 and various pocket knives with can openers. Many other tools will open a can, too. You don't need a purpose-built can opener, but you do have to not need that tool to have a razor sharp edge if you're going to cut a can with it.

The P-38 is not my preferred opener, given the little leverage it provides, but that sucker works when I need it. I do keep it clean and somewhat sharp, as it gets dull with use.