Upgrading the MIM server from windows server 2008r2 to 2012

Hi,

I need to upgrade my MIM sync server and 4 MIM portal servers from Windows server 2008 R2 to windows server 2012.

I prefer inplace upgrade for all portal sevrers since I can take one out at a time from Load Balancer and upgrade. But for MIM sync server I am confused whether to perform an inplace or a new server approach. 

I doubt if there will be any issues to the applications (MIM portal and MIM sync) if we follow any of the above approach.

Will there be any problem with the .NET framework?

Kindly assist me.

Thanks

Rajesh