Consolidating vCenters

[jftwp]

Hi all.  We have 9 vCenters (5.1 U1, all Windows/no appliances), spanning several geographical locations over relatively high speed WAN links. It was previously 6 vCenters at 4.1 back in 2010, then we upgraded all to 5.1 and have added 3 since.

2 of these 9 vCenters are SRM-enabled.  The other 7 are in linked-mode.  We have a single SSO server (centralized) for the 7 in linked-mode, and the 2 SRM servers are 'isolated' and have their own SSO's.  Together, these 9 vCenters manage 'only' about 75 hosts and 750 vm's combined.

Having just come from VMworld, one session on vCenter discussed SSO's, the Inventory service, web client, deployment scenarios and everything else and as the slide deck went on, and it made me think, "Hmmm... why DO we have so many vCenters???

In planning for vSphere 6, why not just consolidate the 7 non-SRM vCenters into a SINGLE vCenter?  That single vCenter could run within the SRM cluster in our primary site, and be recoverable in the SRM cluster in the recovery site.

What are some of the pitfalls of just having a single vCenter for the majority of our virtual datacenters and hosts?  vMotion and svMotion wouldn't suffer since all such operations would still only occur within those virtual datacenters (which happen to be located in different geographical regions).  We have high speed links (nothing slower than gigabit except for our London vCenters).  Authentication might be a little bit slow for remote admins outside of the SSO site but we're already used to that.  vCenter<>ESXi host agent communication would be affected since it would no longer be at LAN speed but again our WAN links are pretty fast overall.  We don't have any 'political' barriers where administration and security and so on might necessitate such administrative boundaries.

I'm just trying to think of any gotchas before planning on a pre-vSphere 6 consolidation of vCenters.  Thanks for any feedback.