I've heard pro-VSTS folks slam the OSS tools for being tinker toys and difficult to integrate (not in my experience, but it's their story), but many of these same pro-VSTS folks sell consulting services to set up VSTS. If VSTS is so easy to get up and going, why are people able to make a living doing just that?
Because when you are integrating OSS tools, you are wasting your time. When you integrate TFS, you are being enterprisey.
(Yeah, cheap shot, sorry, can't help it)