Because MS whitepaper
Microsoft Exchange Server 2007 Service Pack 1
Does not provide with any guidelines for Hosted Messaging and Collaboration version 4.0 Migration Kit when in the environment has been already deployed Exchange 2007 SP1
I would like to now if some one has tested this scenario, or I need to use the kit to migrate from HMC 3.5 to HMC 4.0 RTM and apply after that Exchange 2007 SP1 and related hotfix
Any input to this topic will be welcome
Juan