Even things with moving parts, it would be nice to know that model X of brand Y has a MTBF of 4.5 years, but hunting the same model X 4.5 years later isn't like

Even things with moving parts, it would be nice to know that model X of brand Y has a MTBF of 4.5 years, but hunting the same model X 4.5 years later isn't likely to yield the exact same hardware but some later revision of the same specced hardware.