Guess the opinions are 50-50. This is are 2nd coach. 1st one didn't have them and gal at factory told me when I was asking a ton of questions (being our 1st ever RV), she said if I was considering them ,she would have tried talking me out of it. Thus each time we went out, had to climb up and brush all 3 slides off. Ordered them w/ new coach which has 4 slides and all 4 have toppers. Love 'em. Cannot fully answer about them flapping in the wind. Do sag some cuz when you bring them in after a rainstorm, you learn where to stand and close main door to coach.. I like the idea of installing them in such a fashion that they have a tilt/angle to begin with so water will run off. Have heard too where you can put a beach ball under them to create a Teepee effect. Just don't know how you get the ball out (or in for that matter).
In the end, it's your call.