are we talking about central management or HA here?
Separate locations should not be a problem, but for central management it is important that each node can talk to each other (e.g. bi-directional communication is possible). For HA it is important that some data is exchanged via multicast/broadcast messages, so you have routing between both nodes you may run into some issues.
thanks for the quick reply. Basically the network setup is "Proxy HA". The two applicances are in a cluster and central management is also configured, but only on this two nodes-we have a separate VLAN in which the management interfaces are. So each appliance has two interfaces..the management interface and the interface for user traffic. hope this answers you question.