I have a 07 LTZ Suburban, with a active onstar sub, I picked up a 2010 Escalade VCIM, I read everything
in this thread before I tried to do anything with it and came to the conclusion to go to my GMC dealer and ask them if they could program the escalade VCIM to match my VIN and vehicle info and they said sure, so I pulled my stock one out right there and installed the Escalade VCIM and he took about 30 mins and brought it back to me and handed me a sheet of paper stating it updated to my VIN, I explained to him after what I was doing and he told me he has never heard of anyone doing it before me and hoped it works.
So I called onstar from the suburban and told them the dealer had to install a new VCIM and I was checking to make sure everything was ok, they said yes all is good.
Bluetooth works great and happy as can be, onstar works great, but remote link wont work because onstar thinks its a 07 so they say its not compatible with it, but I tried to explain to the onstar dude I have a 2010 VCIM and it is, but he still said it wont work so I left it at that.
Everything works fine, so I want to thank everyone for there advice in this thread because it kept me from making any mistakes.