I have 4 SA saddles on 4 of 5 bikes. One of those is a NSX, the others are X series. Riders weight is the man difference between the X and H series, as well the rails.
The first one I bought, was a blemished X series, at a deep discount. I have yet to find the blemish. What sold me, was how easy the break-in was, I mean, 30 mile ride, no sore butt. Then I bought another blemished X series, beautiful. Next was a new X series , then I wanted a classic NSX series. No cutout in the middle. I got that one at Christmas, I have only used it on my trainer bike. It's a bike I don't ride long distances, so I'm not to concerned about feel.
I have over 600 miles, on each of the 3 , X series saddles. Absolutely comfy. Feel free to contact SA, if you have concerns, they will get back to you.KB