I am totally with you.. I am still waiting on my F90BT. Once it is here, I am going to take a look at using the SD card I am using for my Mio 320. May be the TomTom on the Sd card may run on Pioneer too.
Once we are able to bypass the pioneer UI, which is loaded rightafter the win CE is loaded, we could run any program which is compatible with Win CE(or for that matter Windows Mobile w/required libraries.) This opens up lot of poossibilities of converting the unit onto an expensive Car PC.
The advantage of doing this is we do not need to wait for pioneer to release for firmware updates.