I have both. My experience with the cover is that it is very troublesome to install: i) difficult to center on the wheel to keep the brake pad from rubbing against the cover edge; ii) hard to align the two halves. To make the set up process goes faster, I had to tape one cover half to the spokes to keep it from shifting around. I didn't have a spare wheel so switching the cover on and off from the wheel is time consuming. Also, the chain has a tendency to rub the cover when it is at the highest cassette cog. When the wheel went through a pothole, I could hear rattling noise.
Solid disc wheel on the other hand is so much easier to set up. I had seen used ones on eBay sold for $150!