Sheldon means you'll be able to feel the rear tire lose traction as it lifts up. This is the maximum braking capacity of the front brake.

For future reference, any time you're jamming on the front brake make sure you lean back to counteract the weight transfer, otherwise... yeah, you know.

Also, I hate to ruin your expectations of something life-changing, but the whole "pure experience" thing is largely a bunch of pseudo-Zen crap touted by people like that guy who claimed that aluminum bikes feel square while steel bikes feel circular. The only time I feel unusually well-connected to the bike because of the drivetrain is riding VERY slowly alongside foot traffic where I can alter speed as necessary with my legs. While actually riding the thing, it's just a bike with one gear that can't coast. They look simpler, have fewer parts, and are easier to maintain, but a fixed gear bike isn't some kind of path to Nirvana.