We had an 11:35am for the Bon Voyage breakfast on our past trip and we had great character interaction and excellent service/food. We never felt rushed. If anything, our server was really pushing us to settle in and relax.
I also think a lot hinges on management directive and your server. We've had last seatings for breakfasts before and had wonderful food and service and have had others (sometimes in the same trip) where it was clear that they wanted us out as fast as possible. Case in point, we had the last breakfast slot at Crystal Palace last trip and they made sure we saw every character and got plenty of food, but a couple of days earlier at our late 'Ohana breakfast, it was very clear our server wanted her shift to be over and the characters were more rushed. Then again...we've also had first seatings (1900 PF day before Christmas Eve) where it was a speed dining experience and most people were up and leaving after 30-40 min...like they didn't want to get behind at the start of the day so the characters were rushing through in an assembly line and servers were pushing the check on you at the 30 min mark. Bon Voyage at least has courses...so in theory...they should be giving you time between pastries, fruit, and entree.