Hire as many cloud or SAAS services as you want. They're a great way to get services without paying to build them.
But build a backup anyway, and make sure it's not another cloud service built on the same infrastructure.
A lot of cloud services are hosted or co-located at the same massive data centers, which provide services to other service providers rather than directly to end users.
If your primary SAAS provider and your backup are housed in the same data center when the meteor comes down and all the sysadmins are eaten, you're still out of luck.
So are they. But that doesn't help you much.