I'm pondering .
My guess is the size issue is much ado about nothing...as the great William Shakespeare might say.
That's they way I see it on Carnival. I've sailed the smaller Holiday ( now adios to Spain) at 50,000 tons 1,500 pax.... up to the 113,000 ton, 3000 pax Splendor . I would say that a "Fun Ship" is a "Fun Ship" for the most part.
Before sailing on a mega-ship I assumed that I would be lost in the crowd. That's yet to happen. The shows were the same, the food the same, the crew/staff the same, and activities the same ship to ship.
It did seem that the Destiny, Valor, Splendor, and Triumph had a noticeable smoother ride. So my vote is ...bigger is better. :-)