We didn't have the slide toppers on our first camper and definitely wanted them on our second.
The first thing we noticed is when camping down south, the slide outs get hot. The toppers keep the sun directly off the top of the slides, which makes for a much cooler area.
Then there was the debris issue. No more pine needles to clean off each time we retracted the slides. Stop run em out, and just run em in when ready to go. With the other camper, I had to clean off the area before retracting, even if it was an overnight.
And lastly, one less chance of a leak during a rain storm. Yeah, it does occasionally rain when camping, even if I order up sunny skies for the whole trip.
2008 Toy Tundra DC 5.7L Bagged w/LTs
2012 Windjammer 3001W, Atriumed