Actually I think that subrella is acrylic, not polyester, and not that it matters. It is commonly used for boat canvas like dodgers and bimini tops and lasts just short of forever in the sun or rain.
I have a Cal Mark cover, they were easy to work with and it does fit and protect well. But it is a bit heavy and cumbersome to put on and take off - substantially heavier than the light weight disposable kind from CW. I'm sure it will outlast 4 or 5 of those, but I find I put it on less often because of the labor involved. I left mine on over the Winter and didn't see any problem with it. It will not keep the roof dry though it will shed most of the water. It will also not keep the roof wet, when things dry out as the material is permeable.