HD Dish Covers

I have a 2-unit duplex with two HD dishes on the roof and with winter right around the corner I need to start thinking of a way to keep the snow from accumulating. I've seen a few places around the area with a canvas or vinyl dish cover and I just wanted to see if anyone here has experience with these. Any signal loss? Does it keep snow from blocking the signal or does it give way to a heavy snow?

Any insight is appreciated! The roof pitch is too much to risk climbing up in the winter and it's out of reach of a long pole with a sweatshirt tied on the end (my old method at another location!).

If they work as advertised, any brand or website recommendations?