Pedal assist is exactly as you described it. However, the bionx system and torque sensor are the best that I have ever tried. I don't think of it as having to reach a "threshold" for the motor to kick in. It detects the pressure or torque applied at a very, very low threshold/pressure (about 1/4 through the first pedal stroke.) It's not ... BAM! motor is cranked up and jerking you down the trail type of "kick-in"... the transition is very smooth, natural, and quiet (I mean silent... you don't hear a motor.) The bionx system does come with a throttle, however, I chose not to have that installed (mostly for aesthetic reasons) and I can't say that I would use it if it were on the bike (seems to be a common statement by most bionx users after they have been riding it for a little while.) Yes, bionx is seamless... much more so than the many other systems that I tested. The Bosch center drive is well integrated and responsive, but you do hear the motor "whirring" a bit on the bosch. I think that the silence of the bionx system is what has been the most unexpected surprise to me. It's fabulous with a steel touring frame, longer wheel base, and the new schwalbe marathon plus tires are smoooottthhhh.