Re: pooling of rain. In the past with my vinyl toppers the pooling would stretch them, birds would bath in the pools etc. I used to get up on a ladder and push a long broom handle between the slide and the topper (after the rain stopped) to get the rain to run off. A hassle but doable. After replacing the Carefree Vinyl twice (due to rips and rotting) the last time Shade Pro (El Cahon, CA) recommended acrylic for longer life. That was this past Nov. The first time it rained, the pools were 8" deep pushing the toppers right to the slide roof. The broom handle trick did not work as the acrylic is very light weight. With at least 50 gal of rain water on each slide, I wanted it off. Pulling the slides in slowly got some off but the weighted down acrylic material sucked in on top of the slide as it went in. The only way to get the water off of the toppers is to climb on the roof to sweep it off the toppers. I called Shade Pro about this problem and they explained that this is the way acrylic material is.....its too light for rain. I have tried the commercially available AIRWEDGE with very limited benefit. I have resigned myself to getting on the roof after each rain. In my mind...a hassle.
As far as snow....The problem I have encountered relates to wet snow, the light fluffy kind will fall off as the slide moves in. The wet stuff packs itself on the topper and rolls up with the topper. Before the slide is all the way in, the topper roll is so big it no longer retracts. You must clear the snow from the topper before retracting the slide. The problem is even worse with the Carefree as the roll is covered and clogs up faster than the A&E.