We have had toppers on all our trailers from 1997 to the present and would not be without them. They help keep the top clean from debris as already mentioned and also keep rain and "other" dropping stuff off the top of the slide.
To clean the slide top itself, about once per year I will use a ladder and run my wash brush over the top to get the dust or anything else off of it. I also use my wash brush with one end wrapped with a rag to apply any seal treatment when I feel the need (not often!);)
Since everything rolls off the topper as you bring in the slide, we have never had to climb any type of ladder to clean it off. If necessary I sometimes stand in front of the slide with a broom and broom the roller as the awning rolls up. This removes any stubborn leaves etc.
The reason the poster mentioned in jest to have the wife stand beside the awning is because as the awning rolls up, any water standing on top will pour off the side of the topper. Which side kind of depends on the tilt of the trailer front to back. If perfectly level, then it will pour off both sides. I doesn't pour off the front because of the slight rise as the awning rolls over the roller. Wife will get an unexpected shower if she stands on the side.
Basically, in my opinion a slide should have a topper, and they are relatively maintenance free and trouble free while giving a lot of protection.
Barney
2004 Sunnybrook Titan 30FKS TT
Hensley "Arrow" 1400# hitch (Sold)
Not towing now.
Former tow vehicles were 2016 Ram 2500 CTD, 2002 Ford F250, 7.3 PSD, 1997 Ram 2500 5.9 gas engine