After considering the apparently big differences between the Microsoft and the Widcomm Bluetooth stacks, I found out that there is a way to make them work under a similar API. This is especially useful for Compact Framework developers although some native developers may also benefit from a simple C type API.
The Widcomm API is oriented to C++ developers and exposes itself as a set of C++ classes that are supposed to be consumed either as-is or derived in your application. Exposing this type of API to a .NET CF developer is nothing short of impossibe unless a C layer is developed to consume the Widcomm stack while exposing a set of simple functions.
While I was writing this piece of code, I found out that the Microsoft stack could also be subject to the same treatment. So my idea was to produce two DLL files with exactly the same function exports, one for the Widcomm stack and the other for the Microsoft stack. The obvious advantage of this is that now a .NET CF application can consume the existing Bluetooth stack without having to consider the differences between the Microsoft and the Widcomm stack.
I have to say that this was a very interesting learning project, thanks to Peter Foot's help. The resulting code will be published under a series of articles and, time permitting, I will try to integrate the code in Peter's own 32feet.NET project.