Sitbone width is only part of the story, unless you ride an upright bike; then s.b. width is the whole story. If you lean forward at your pelvis to reach the 'bars, your weight is carried by your pubic rami, the bone structure between sit bones and pubic arch. They appear to be curved, and the space between them gets narrower as the bones go forward to the pubic arch. My bet is that the rami are more significant to seat comfort than saddle width.
I used to ride at 240. The Serfas Rx started transferring its fabric to my shorts while I building up miles, so I never did actually test it for comfort over the long haul. The Fizik (who was the branding schmegegi who named them?) Aliante was good for maybe 15 miles before I felt numb. The Brooks B17 Imperial (a B17 with a slot) was a little better than the Aliante. One of the ISM 'performance' series gave me absolutely no numbness, but the weight on my pubic rami gave me a hard to get rid of saddle sore.
The saddle that works best for me is the Selle SMP TRK - not expensive, too much padding, but it works ... except it may stop working soon, because my butt has changed as I have lost weight. In any case, see if you can find their patent application, or look at the documentation on ismseat.com to find out about the rami vs sit bones issue.
A soft seat allows a rider to sink into it, which can put pressure on the pubic artery and nerve, and that leads to pain and/or numbness. A hard seat supports a rider's weight on the bones, which keeps pressure from the soft tissues and thereby prevents pain and numbness.
Which sounds great - except that a good leather seat conforms to a person's anatomy, which seems to mean that soft tissues aren't protected against pressure once a Brooks, Ideal, Wright, Berthoud, etc. leather saddle breaks in....
Alas, no theory has allowed anyone to create a saddle loved by everyone. We're left with the necessity of trying seats out until we find one that feels good.