Ditto about making the flight home later in the day. Then you could have two days at Universal.
You definitely will be off the ship early, so you'll have that whole day.
If you are like we were, though, we were pooped! The last day of packing and stuff was a bit tiring. If we ever did another cruise, Disney or otherwise, we wouldn't have brought so much stuff! We ended up not dressing up much, and one little dress doesn't take up much space. Didn't do any of those photo shoots or anything, and my kids would rather eat by the pool than dress for dinner (or one outfit could be fine all week really). I wouldn't bother with our snorkels either, they take up so much space and the water wasn't clear enough. Plus if you booked an excursion through the cruiseline, I guess they'd give you the snorkels to use on the excursion. I would just bring a small carry-on type suitcase like we do to Orlando, and then carry it off with me when I left the ship. We each have our own ones, we're bringing them tomorrow to US.
So, if you have a lot of energy, I'd do it. We were just tired and ready to get home - wish we had booked an early flight from MCO but had an afternoon one. Hung out at the airport, and were tired!