Do you have a preference as to which service is the Master list for you? Some people utilize their Exchange for everything including personal while others only merge personal and business inside of Google or their personal PC with Outlook.
I began using Google as the master account holder for all things related to my services. This makes it easy to export, maintain and sync contacts. I stopped using Outlook/Exchange but that doesn't sound like an option for you.
When I was using Outlook I would simply clear out all contacts in my phone, outlook and make sure that Google had the correct info/dates. I would then go use an app called GoSync ( i think) to sync Google to Outlook/Exchange.
I guess it depends on how you are interfacing with Google on your phone and what phone it is...on my WM6.5 phone I was simply using Gmail Exchange to do all this.
Wow, I typed all that and don't know if I added one answer...did any of that make sense?