But, you could always look at third party tools for coexistence as well. I might suggest looking at BinaryTree’s CMT for Notes to provide the migration of users and CMT For Coexistence. Depending on the number of users you are planning on migrating, these tools can provide tremendous benefits over the Microsoft Connector alone.
SMTP Traffic between Notes and Domino is not very conducive to both environments. Changes to iCal formats are no consistent and you may encounter significant problems with repeating meetings in both directions. This Coexistence solution will correct as much as can be possibly done.