Update from the kind folks at Synthesis (aff link):
Huge credit goes to Frederick Townes and the W3 Edge team for being proactive and diligent in correcting the issues that several hosts encountered. W3 Total Cache is a great plugin, which is why we recommend it to every site we host as well as providing Synthesis-specific settings in your welcome email.
Update and deploy with confidence!
But for now – leave your W3 Total Cache UN-upgraded. There have been some issues with upgrades that are wide spread enough to warrant a bit of caution. Check back to this post for updates and when we think its safe to upgrade, we will let you know. This information comes from the smart people at Synthesis, who I trust with my hosting needs, and recommend exclusively for anyone who gets more than 1,200 unique visitors a day to their WordPress site.