I have been using RemGrit-type carbide blades for years. When you need one, nothing else will do.

I live in a converted farmhouse with plaster (stoneboard) walls. The only way to cut electrical outlets into this stuff is to start a hole with a masonry bit and cut it out with a RemGrit blade in a sawzall or jigsaw.

Once, I cut down a heavy Chinese machete blade with a rod-style carbide saw in a hacksaw frame. It did the job, eventually, though I got a good workout in the process. Also burned myself twice; these things get really hot.

Another time, I needed a stubby wrench for a repair. The hardware stores were closed for the long weekend, so I cut a surplus combination wrench in half with a carbide saw. (My angle grinder wasn't working at the time.)

Carbide saws clog in soft materials, though if you put on extra pressure they will continue to cut. Not ideal for that sort of job.

If I carried one in an emergency kit, I wouldn't think of it as a replacement for a standard saw. Rather, it's a super-abrasive that, with time and patience, can cut literally any material.