Hi,
I do not like SSO. It unnecessarily complicates things which were simple before. To me its an answer to a problem that doesn't exist.
We are planning similar. The main headache was to ensure that no part of the installation was reliant upon the protected site. We did not have confidence in using SSO in a multisite configuration when there is no solid documentation on configuring clustered hardware LB's to provide a singe SSO source.
In our case we have designed a totally independent SSO, vCenter and SRM installation. SSO is using the local AD copy at each site. They are not running in linked mode, so must be administered separately. Because the SSO installations are totally separate, the groups and users must be manually edited at both sites. This could be a headache if you have a lot of changes.
I'm not sure how VM specific permissions would fail-over in the case of SRM, or even if SRM replicates them anyway - I've not got there yet. It would be nice to think that as long as the same SSO users and groups, and the same roles and groups in vCenter exist, that SSO would replicate the permissions to the placeholder VM's in preparation for the failover...
As far as I understand it, SRM doesn't to automatic failover - it's more like a big red panic button. I would not like this to be automated in my environment, and then have to deal with the failback.
Regards,
Rob.