After recently acquiring a bike with a narrower saddle, I decided to give it a try "temporarily".
I'd lost close to 50 lbs. over the previous year and had a noticeable shrinkage of the posterior.
I'm sticking with it. I seem to get a bit more force AND cadence.
I raised the seat to accommodate the "less splayed" position of the knees.
I seem to spend more time in the "thrust zone" and less with the knee at max bend.
That's MAJOR to me with my bad knees. I've had to go to 165mm cranks to avoid knee pain.
It basically made me feel like I was spinning like I was 5 years ago. I'd probably lost 5 RPM on my cadence.