Which version of the .NET SDK are you using?
If you are using v2.X of the SDK, you shouldn’t have any issues. For the most part the same is true for v1.3.X of the SDK, however any new features available in Couchbase Server will not be available for use with v1.3.X because all new development is being done on v2.X.
I am not quite sure I understand the question…the data itself will not be changed by the upgrade.
-Jeff