I ride a couple of them. I
I ride a couple of them. I started with the SMP4 Bike TRK (which is now relegated to the turbo trainer bike) and then changed to an SMP4Bike Hybrid for my everyday bike and SMP4Bike Pro for my better bikes
The advantages of the hybrid and pro, imo, are the narrower nose. Narrow enough to make for free and easy pedalling.
Also, I tend to sit forward on the saddle a lot when I am trying and ‘the beak’ is very comfortable in those circumstances.
You can read some of the science and see pretty much the full range at http://www.smpsaddle.co.uk