We have considered this, but our current focus is to catch-up to the SugarCRM release.

A fat client would not be that hard, especially given that most of our forms are generated dynamically.  Most of the logic of SplendidCRM resides in stored procedures in the database, so this will also reduce the effort.

Before we create a fat client, we will likely migrate to the .NET 2.0 Framework.  This will give us tremendous power and should significantly reduce the effort to create a fat client.