Never mind, I found my answer after some time researching. :-)
As I suspected it's a DLL dependency issue, but not for the reason I thought...
The other problem is that in my VM I have installed AppFabric 1.0 whereas in W7 I just installed version 1.1, and go figure from the release notes: http://msdn.microsoft.com/en-us/library/hh361710.aspx
Caching assemblies are no longer registered in the Global Assembly Cache
In the previous release, the AppFabric Caching assemblies were registered in the Global Assembly Cache (GAC). With the release of AppFabric 1.1, the caching assemblies are located in the installation directory (defaults to .\Program Files\AppFabric 1.1
for Windows Server). When deploying cache client applications, you can deploy these assemblies locally with your application.
So as you would expect, if you copy the following files:
either to the entlib configuration tool folder or to the GAC, now you can see the custom provider showing up. :-)
The thing that annoys a little is that there are no exceptions or information on why the import failed (I didn't see anything relevant on the Event Viewer).
Also very weird is that the Sharepoint Trace Listener I created also references an external DLL (Microsoft.Sharepoint.dll) which is
NOT present in my Windows 7 machine, however the provider does show up in the configuration console, how is this possible?