These are my assumptions but I'd like you to correct me if I'm wrong...
If the system drive fails, I lose all my computer backups. This is not a problem because there's still the real computers, so I just need to change the system drive and reinstall WHS.
But, what happens with the data stored in shared folders that are duplicated across drives? Does this data become unreachable once the system drive is changed or is it automatically discovered by the new install of WHS?
In summary, I don't care too much about computer backups as the possibility that a computer fails at the same time that the WHS's system drive is pretty low. However I do care about the files stored in the shared folders as WHS is the only place they exist.