Two things...
1) Isn't there a SLA we do with them when we sign up? Remember the 99% uptime guarantee?? So yes, if that's breached, we CAN sue them.
2) Why bother with point 1! Instead get a good, low level VPS from a quality provider, AND ALSO get a cheap shared hosting.
Then use amazon route 53 premium DNS and keep the cheap shared as a backup for your most important sites. When (if) the VPS ever goes down for some time, amazon will automatically route your site to the cheap hosting (yes automatically!), voila, no downtime technically! No rankings lost!
Although yeah it is time consuming to clone the sites and keep them updated... but for your main bread winners, its worth it!