Step-in bindings suck compared to normal strap-ins. You don't have the stiffness, feedback, or response. I've tried them, it just doesn't compare. Burton tried their own system a few years ago only to discontinue them. If Burton can't shovel their step-ins off on the kids who would normally pay $99.99 for an authentic box of dog shit with a 'B' on it, they have to be real garbage.
Step-ins do have the speed and convenience factor, they also have a small, loyal following, but performance-wise, they simply aren't competitive. This is why you see fewer and fewer of them each year. The reason most rental shops use the old switch system (type of step-in) is b/c of the versatility (you generall don't have to switch plate sizes depending on the renter's boot size), the durability (no straps or ratchets to break), and the fact they've already got a lot of money sunk into establishing it as their rental system.