I'm doing some testing right now to see how much W3 Total Cache might be able to help us out on top of the fact that we're using nginx as a proxy/cache server in front of our apache install.
However, one of the biggest issues I expect we'll run into if I turn W3 Total Cache on on our production server is the fact that the W3 Total Cache cache doesn't seem to clear itself out when a new widget is added to any of our sidebars, or changes are made to a specific widget's settings.
It would be nice if W3 Total Cache could be configured to dump the cache when changes are made to widgets on the site.
If that's not possible or likely, it would be nice if the plugin could at least post an admin notice informing the user that a change was made to the widgets, and that they might want to clear the cache themselves (similar to the way the plugin handles new plugin activations/installations). Thanks.