You might not have the right SQL Servers on your ESX system, or it might not be sized. I know of 4 companies in the Denver area that run it and have done so for over a year. They are thrilled with the way it works in that they can save on hardware, but more importantly, space and cooling. However many of their larger SQL Servers, for things like ERP, have not been moved. The performance, and the scale is not there.