Businesses and enterprise users would likely prefer an organisation with a proven track record (eg rsync.net) anyway -- even data replication aside.
But this seems to be a beta phase so I guess it's more important to iron out the issues around creating a business that works, then you can have more drives in your account.
>Rent out multiple drives if you wish to create a RAIDZ or Mirror ZPool.
Zpools with the correct level of redundancy protects against bit rot, occasional hardrive failure and the like(as you correctly point out), but not against total machine loss.
Its probably helpful to think of it as an offsite backup more than anything else.
> Rent out multiple drives if you wish to create a RAIDZ or Mirror ZPool.