I've refoamed a stock K0 seat and tried a few repro's The DSS seats are nice, the pan and appearance are good and I think maybe they got past the Honda logo ban. Although I believe them to be more firm, I only have old used, old unused and at least one NOS K4 seat to compare to. My butt thinks a brand new K4 seat was softer but that was long ago.
There was a repro company that sold thick non seamed (maybe boat vinyl) seats, I have a k7 and once had a gl1000 they did and hated them immensely. The foam shape and hard vinyl caused you to slide forward constantly. I cut up the foam on the gl1000 seat at Mt. Rushmore campground and the 15 hour ride home was much better. If your thighs carry some of your weight the ride is a lot better.