Unless I'm missing something then you'll always stop faster from 25kph than 38kph because for the same weight of rider you'll have half the kinetic energy. Assuming riders of equal weight
Yep ... but starting at the same speed LWaB would always outbrake me, so I was giving myself half a chance to win (even though I would be starting with higher cadence)!
I think I'm right that the closer you can get to the skid threshold the stronger is the braking, but how one factors in the effects of gear ratio and cadence is beyond my applied mechanics, so it comes down to experimentation and experience.
Back on topic, nobody has mentioned risk compensation
I
think I'm a little bit more cautious when riding front brake only ... mainly downhill when the back brake is safer as a drag to scrub off some speed.
But in reality if I'm out of town in flattish territory I can ride for weeks without touching the brake(s), and in these circumstances fixed wheel is a joy and I don't worry whether I'm running one brake or two. However two brakes will always be both safer and more versatile, so I'm sure Chris N has made the wise choice.