It is very common for most customers to really wait until a product gets more mature, wait to see the trends and evaluate if they should migrate or not. Questions like: who is adopting this platform? what advantages I will have using this new product? why should I migrate my stable ISA environment to TMG? Those are very common and understandable questions and the fact of the matter is that there is nothing better than real world case scenarios to really answer those questions. If this is your case, then take a look on the Forefront TMG 2010 case studies page at http://www.microsoft.com/forefront/threat-management-gateway/en/us/case-studies.aspx , this should help you to make your decision.