Yes, you can run the Microsoft Dynamics GP web client and desktop client in the same office. For that matter, on the same server, even the same workstation. The choice isn't "either/or," nor does it require two versions of Dynamics GP.
GPUG recently hosted an encore presentation of a Convergence 2015 session on Dynamics GP mixed deployments, presented by Brian Allrich, a senior software engineer with Microsoft. Allrich emphasized that the web client is not an all-or-nothing deployment; customers can deploy both the web and desktop client on premise. A good many do, and he used the event to both review the benefits of the current web client (a