I have both style covers. I use the Perma-Pro on my E-21. I have used it about 10 months (two seasons) in the Fl. winter sun. It is made of ripstop material which is light weight and compact for storage (Good for a larger cover.). The gray cover is beginning to fade but no holes or rips. The ripstop cover drys out quickly  and less prone to get mildew under the cover.

I have a 10 ft Model 1 on my Little Joe in Fl. and a friend uses one on his S-13. The cover is a little thicker made out of material used in cheaper car covers. I bought a Casita with a cover like this. These covers take longer to dry out after a rain. The Casita cover had developed a little mold under the top. I installed the cover 4 months ago on my Little Joe in Fl. and have not had a chance to check it durability to the sun. The inside material on this cover is more prone to pick up trash and hold it if it hits the ground.

Both covers are about the same price. They both can tear if snagged. Trailer cover and pool cover lifetime warranties are for the lifetime of the cover. If I get more than two years  use out of a cheaper cover I feel lucky. It's kind of a toss up for a few dollars difference but I think I like the rip stop cover (Perma Pro) just a little more.

Eddie