"Fast or sporty" are pretty subjective measurements. What is "fast" and "sporty" ? Are we talking speed in a sprint, or speed over miles? Are we talking about "sporty" in terms of handling? Frame geometry makes more difference there than tires. And is that a desirable characteristic for the kind of riding? In a sprint or a race, definitely. How about on a weekend ride? Commuting?

Personally, "on the planet I live on" I find that on softer tires I actually ride faster over distance because I fatigue less. All that vibrating, jittering and slamming over bumps is not good for you, it's not good for your wheels, and it doesn't improve your time. Sure, on smooth roads in a short distance a thin rock hard tire will be faster. But you'll get tired faster and on long distances you'll blame your saddle for your sore rear. I like to push my bike hard, too, it's fun. But I can cover more ground faster on a soft tire than a hard one any day. I tire more slowly and I keep the pace up for longer.

I don't have any 650B bikes yet, but I will! I ride as fat a tire on my bikes as I can get/afford. 650B is the next step.

Karl