I'd really recommend against using the Bria standalone client.
When using it with GAD I've experienced the following issues, amongst others that I've probably forgotten:
1. Audio randomly dropping out for a few seconds mid-call;
2. Delays in connecting the two parties at the start of a call;
3. Garbled audio when retrieving a call from hold using the GAD (pressing hold then retrieve in Bria resolves this);
4. Bria volume control randomly muting itself;
5. Bria application crashes;
6. Bria loses connection with SIP Server but GAD stays in Ready status, leading to dropped calls;
7. RTP inactivity timer does not work correctly (If an agent puts a customer on hold and initiates a call to a 3rd party with the customer still on hold, after 30 secs the call is cut off. The timer was not even set to 30 secs! Deactivating the timer resolves this)
To make things worse, each new release of the software introduced a new issue.
Deployment of the application is also a particular challenge with more than just a few users because there's no mass deployment solution and all the settings are held within the user profile.
The main issues seem to be caused by the poor interaction between GAD and Bria. Although the Interaction Workspace SIP Endpoint uses Bria's technology, it sounds like it's much more tightly integrated. I've just begun looking at this so will update here if any problems!