Grid communications take place through VPN tunnels so as long as that tunnel can be maintained, you should not see any issues. The Infoblox Grid is engineered to handle Grid members that disconnect and allow them to continue to operate in an offline state and the average network link is more than adequate to handle the Grid communications.
Where you would be more likely to see potential issues are with upgrades and viewing the logs and configuration files, processes that can involve large amounts of data being sent back and forth.
