I bought the Sargent seat for my NineT and was disappointed... at first. I now have about 2500 miles on it and it is starting to feel good. It is softening up a bit as it breaks in. I'm mentioning this because if you get the Sargent, it may actually feel harder than the stock seat when you first try it. It is definitely wider and shaped a bit differently so that you are being supported by a larger area, but the foam is quite firm at the start.
I have every confidence that the NineT Sargent seat will get even more comfortable over time. I have one with over 30K miles my 2016 R1200RT and after breaking in (I'd say it took 5 or 6 thousand miles) it is now good for 500+ mile days for me.