It's a bit of a quandary, having a digital camera but choosing only to shoot in B+W. Don't Lecia have an exclusively B+W digital model on the market at the moment?
Personally I prefer to shoot in RAW when using digital and then doing the conversion in Lightroom afterwards because it just gives you more choice and control.
When it comes to film I typically shoot B+W as its much easier to develop. I personally prefer it to digital B+W also, I rarely manage to get a digital B+W conversion that competes with the sheer beauty and honesty of B+W film.