Sit-bone measurement

I finally measured my sit-bones yesterday and found that this had been done incorrectly in the past. I did it twice, same result. If I have sit-bones that measure center-to-center at 5.25 inches, I am assuming that the 160mm width of the Diva Gel Flow is not too wide. It seemed to feel fine for my sit-bones - but I wanted to make certain that this makes sense before my demo period is up. The rear cut-out is 4 inches wide - so I can't see how the cutout is overly wide.

The 40-mile ride Saturday will certainly help me make my mind up as well - last night my short ride was perfect. However, for someone getting into long-distance riding the operative word in that sentence is "short".