I have them on our Landmark and I'm not missing cleaning leaves and other stuff off the slides before closing them. I also don't worry about water getting dragged in with the slide, to whatever extend it might.
On the other hand, when it's very windy, the toppers can flap and make noise, and snow can be more of a problem. I use plastic baskets to deal with snow. Others use pvc supports, beach balls, and other devices to provide support in difficult conditions.