Hybrid deployment for MS Exchange is the norm for very large environments for a number of reasons.
Hybrid environments are hard to manage because they involve multiple hybrid services such as ADFS, Azure AD, Exchange Edge server and, sometimes, mailbox servers. Some subsidiaries are on-premises while the group is online in the cloud. Security and compliance are also issues. Of course, all the other online services need to communicate and integrate perfectly with Office 365.
As if that wasn’t enough, your route to the cloud and your internal network are charged with delivering the best possible end-user experience.
Fortunately for you, your complex MS Exchange environment is where GSX Gizmo excels—to monitor and report on the quality of service you are delivering!