@sshughes My understanding of the system so far (but take that with a grain of salt, in real life I'm sort of an accountant who's only larp'ing as a sysadmin here): the system is not meant to 'run on a single host and when it dies we replace it'.
It's meant to run on three identical hosts which never all die at the same time (except for some GBU hitting their building). Therefore there is no focus on 'let's reconnect new hardware to existing SR and fire up the VMs stored on that SR'.
After planning accordingly, I can live with that. Planning accordingly in my case means: 'well, if my single host dies (running two or three isn't worth it for me), I'll take a day of down time to restore from backups.'