I purchased my boat new in 2013, and also got the "Premium Deluxe" (black) mooring cover. The boat sits in a covered slip in the summer, and in a sealed metal building in the winter. In the three years I've owned it, it's had about 5-6 days of direct sunlight and hardly any moisture. In only three seasons, it has completely fallen apart.
The ratchet teeth are worn/won't hold, the zipper over the starboard side ratchet seized up to the point where I had to cut the zipper off, the Yamaha lettering is all cracked and nearly gone, and I've already had to replace two of the plastic buckles (replaced with these:
https://www.amazon.com/gp/product/B00DG83CQW/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1)
It's had a very protected, easy life. Not sure why it died so quickly.
That being said, the cover they offer now looks to be much nicer, like a new revision. The hardware looks better, the cleats appear to be all covered now too with some sort of more reinforced pouches/cases. I'm going to try this one and see if I can get a little more than 3 years out of it.