mlam, just had my session today with my 4 month old boy. I have to say that we all had a great time. The photographer was really good with my baby, and he actually laughed and had a great time generally, and sustained throughout the one hour session, much to my surprise.
I have to say they are not really like your typical photographer, and I understand that their product is really expensive. With them, I suppose you should not think of them as "photographers", as the end product will probably be more like one piece of artwork, from what I understand.
Well, just bring in whatever you would like to be photographed, especially bright colours, as they will look great with the white background.
I will have my viewing session next Sunday. Will let you know how that go.