A 300 mile day is approx 6 hours of time, over that period a 2013 CB will need to be fed about 5 times, and the rider once. Plenty of breaks to rub the bum, walk around a bit. broken into 125 mile segments I would think it would be no problem for you on either seat, but then again some say they can't go 1/2 of that on a stock seat. I have spent multiple 9 hour days on both seats and yea eventually you get a little bum sore, but I think that will be the case no matter what seat you are sitting on. I start squirming after sitting on my car seat after a few hours.
The 13 and 14 seats are not drastically different other than looks.