In our environment we have SRM and Linked vCenters. No issues so far.
One important thing to consider however is the number of opened sessions:
when working in Linked Mode every time someome logons to one of the vCenters in the group, session is opened to each vCenter.
For some reason every time you login to SRM (at one of your sites), it creates 4 sessions, and if you are using Linked Mode, 4 sessions will be opened to the second vCenter too. So single user that connects to SRM at both sites opens 8 sessions to each vCenter.
Large number of sessions may affect vCenter performance (especially in large environments with many users that connect to vCenter) .