My 2017 CB -500F with Corbin seat would disagree with you. It fits fine.That looks great, how ever ,it will not fit on the post 2016 models.
I do wish the Corbin seat were a bit raised at the front, about an inch, but that said I don't find myself sliding forward. I asked Corbin with my order to raise the front an inch, but I got what they decided was what I was going to get. It's still a grand improvement over the horrid OEM seat.