3 vCenter SSO with single site or multi site ?

Hi ,

I am having 3 vCenter at different location. Now I am planning to upgrade my vCenter to vCenter 5.1 with SSO. But after going through the below sites , Am little bit confused wether I should go for multi site SSO or with Single site.

Have anyone implemented SSO with their 2 or 3 vCenter in linked mode ? What would be the best practise and configuration for me having 3 vCenter ?

LINK :

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2034074

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2042849