I see there is lot of confusion around a question if CRM 2013 work with existing CRM 2011 outlook client? Do we have to uninstall CRM 2011 outlook client completely to make things work and install CRM 2013 outlook client?
The answer is yes, Microsoft Dynamics CRM 2013 instance can be used on Microsoft Dynamics CRM 2011 Outlook Client . In this scenario we need to remember that you cannot take data offline by using Go offline. To take data offline, upgrade to CRM 2013 for Outlook.
Make sure you have at least Microsoft Dynamics CRM 2011 Update Rollup 12 applied. Only Microsoft Dynamics CRM 2011 for Outlook with Microsoft Dynamics CRM 2011 Update Rollup 12 or later update rollup is compatible with Microsoft Dynamics CRM Server 2013.
Then, I further read in our CRM 2013 implementation guide and it is explicitly mentioned that although Microsoft Dynamics CRM 2011 for Outlook with Microsoft Dynamics CRM 2011 Update Rollup 6 is supported for upgrade to CRM 2013 for Outlook, CRM 2011 for Outlook with CRM 2011 Update Rollup 6 is incompatible with Microsoft Dynamics CRM Server 2013.
Reference to the content in IG guide:
Here is the link for both the outlook clients:
CRM 2011 Outlook Client
CRM 2013 Outlook Client
Microsoft Dynamics CRM 2013 Implementation Guide