Centralized server can use same AgilePoint license for all teams.
Physical hardware cost can be controlled because all teams can share same physical.
If you prefer to have centralized upgrades for all teams then this is a good option since you can run upgrade once on the server and all teams get upgraded.
Upgrades cannot be planned independently so all teams need to plan for upgrades together.
Offshore teams can notice some level of performance degrade if the network connection to remote server is not good.
The database instance is shared between different regional teams therefore power users from other team who have higher privileges can access information from processes belonging to other teams.
Teams would be sharing the same work calendar which would mean that business time calculations cannot be used for other teams since that would result in task becoming Overdue during their non working hrs. Also holiday schedule cannot be used either due to shared calendar.
Offshore teams can notice some level of performance decrease if the network connection to remote server is not good.