Putting the stuff on was interesting. I put one coat on after inital sanding, cleaning etc, then the other per directions 12'ish hrs later, and 2nd coat was really rough etc. so had to sand that coat down and redo. Found it was best to light sand between the coats to make sure final was smooth. Otherwise, having only been in the boat for a week, and on the floorboards for maybe 3, it looks nice. As far as longevity, you would have to ask someone that has had it for awhile.
I have three smallish boards that are glued into the hull, those were a bit tough to do, and make smooth, but they still came out looking good. I also did the wood stairs/engine cover that was varnish only, Sanded those down, then coated with the US, hoping it would last a bit better than varnish.
Last saterday while installing, a shower came thru, and go the floor board wet outside the boat, water beaded up, tip the boards on there side, and off went the water, a quick wipe off, and they looked clean and shiny!
Varnish I used "top secrete" spar varnish. Either wiped on with a cloth, or a foam brush. US I used a foam brush as recomended too, altho NOT there brush, typical home depot, which is probably what theirs is but marked up a whole bunch.
I forgot to mention last post, material needed was 35 yds for the sunbrella, and 2 more yds of the vinyl used for the ceilings and hull liner etc. This was a bit more than really needed, as we did piping vs non piped cushions that were stock. Many of the cusions ie main living area are contured which cost a few more $$ to make up, custon cut etc.