Re: "If there's a moral to the story it is look after those backups" Not really.
John, I believe the current British Research Concils mandate that experimental data is kept.
For software reproducibility of course containerisation has a big role to play - hopefully the analysis chain and required packages are being captured in Docker (etc) containers which are being preserved beside the data.
c) The instrument specs.
Damn good point. There is no point in having the raw data if you don't have the calibrations.
Look at the hundreds of years worth of weather station temperature data. I believe meteorlogists (sp?) have to be damn careful when the type of termomenter changes at a weather station so there is a true continuation of the measurements which can be trusted back to the old style instrument.