Slides are not for me. I don't want any potential problems. Or drafts, heat loss, etc. The 15K BTU AC is already working hard on my 24'.
In Dec. in Death Valley my friends and I were helping out a guy with new class C with slide stuck out. If we hadn't got it going, I was going to drive him back to Furnace Creek to make a phone call. Typical RV quality isn't that great. Anything left off is one more potential problem left off.
But to each their own. Some people need the space, the slides do really open up the floor plan. I would expect they're a plus in the resale dept. Sometimes they're part of otherwise compelling product.