I'm pretty sure I see a hint of seat rail in some of those pictures, so it should be swappable. Plus, I just don't see any advantage to using non-commodity part

I'm pretty sure I see a hint of seat rail in some of those pictures, so it should be swappable. Plus, I just don't see any advantage to using non-commodity parts for the seat, unless they hope to screw you for the $200 "comfort saddle".