My understanding is that the current Big Thing is to run 23mm tires on a 23mm wide rim. This is done primarily for aerodynamics, rather than comfort. I would think that you'd need to run the same or higher pressures, that the ride would be more harsh and that you might be more prone to pinch flats since you've flattened the tire profile by stretching it across a wider rim. Maybe I'm wrong? You could always try running a 700x20 tire on your current 19mm rims to get a feel for how the new wheelset will work.
I am planning on doing 3x front and back. I don't want to do less than 28/32. Reliability is my primary concern. I want to go with one of the wider rims as I want to be able to run a bit lower pressures, and want to experience the related improved ride quality I hear people rave about.