I actually depend on the water behavior just as much, if not more in the warm months as I do the winter.
Our except for one period that seems to hit in February each year, our winters are fairly dry compared to most with occasional snow and ice storms that only make a nasty mess for a few days. Due to the cold, the vehicles don't get washed very often and I honestly don't worry too much about how they look because, well, it's cold, dark, and often overcast. Cars never look good that time of year.
Spring and summer however, we see quite a bit of rain and I count on the water behavior to keep the car from becoming a spotted mess when I'm at work. Also, the warmer month are when I tend to wash the vehicles by hand the most. That's when I need the car to shed bugs easier and sheet water to make drying faster/easier. I don't want any topper to interfere with the coating's ability to do both.
