This is the thing that's put me off Joyent. They make claims like this one from October 2012:

We’ve given our other partners 99.9999% uptime.

This despite a 10-day outage of their BingoDisk and Strongspace storage services in January 2008, 1734 days previously (http://www.datacenterknowledge.com/archives/2008/01/21/joyent-services-back-after-8-day-outage/).

If you assume that is the only outage they've had since then, that works out as 99.4% uptime. Quite a few less nines...