I have been on over 25 Carnival cruises, and I have never been on an Excel class ship. But it's not because it's out of my comfort zone. I cruise based on destinations and price, and there has never been a cruise on an Excel ship that went where I wanted to go at the price I wanted to pay.
Someday, I hope to at least try it. But right now, I am not one of those people who are willing to pay a premium to do it.