Reciprocating saw for demo work — what's your go-to blade/saw combo for cutting into unknown material?

Demo is the one job where you genuinely can't always see what you're cutting into — old nails, wiring, plumbing. What's your reciprocating saw setup for that kind of unpredictable work, and has a saw or blade ever saved you from a nasty surprise (or failed you at the worst time)?

Rounded up a few solid options here if it helps: https://powertoolslab.com/best-reciprocating-saws/