I think a CMS is very important, but the only draw back with them is the amount of setup, and if you have multiple sites, then they all look the same because of the effort in customizing it.
Our CMS is all in house and each site has its own script that is unique to prevent the "canned" look. It is easier to do this then redo all the customizations for a new site from a 3rd party CMS.
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