I would have to assume (yeah, yeah, I know) the OP knows her son well enough to know whether taking him from school or not is a big deal. I would really love to hear more from the OP. We have traveled to Disney many times throughout the school years and never had an issue. I personally would not set foot in Disney over the summer months. So to each his own! I imagine there are many of us on both sides of that issue!
Our kids are 25, 20, 15, 12, 5, and 2. Every single one of them has had at least one trip that did not excite them the way I would have liked. They did still enjoy the trip, just not the way I would imagine them doing it. Point of our trips has been many faceted each time. to relax for Mom, to see it all for Dad, to ride ride ride for the tweens and toddlers, to see shows for the girls, to do water parks for boys, to shop for Mom, to find something new each time for Dad, on and on it goes. Never the same trip twice.
Hopefully OP will come back on and tell us how it is going! we all know what a tough age 14 can be if only from looking back at our own lives!