I follow a similar philosophy. At the moment, I have two near-identical factory-refurbished x220's, each of which I've upgraded with an IPS screen, 16 GB RAM, and an SSD. One stays at home, and I use the other at the client site.
Even with the upgrades, they still cost me little enough that I wouldn't mind too much if one died, and I've always got at least one spare and ready to go.
Even with the upgrades, they still cost me little enough that I wouldn't mind too much if one died, and I've always got at least one spare and ready to go.