I fail to see how a nozzle would have any effect on the water actually beading off. To me, seems that once the water has left the nozzle, and hits your car, then it's up to however the surface is prepared to dictate how the water goes. Just as being asked if waxed lately. When it's been a while, the water doesn't bead. However waxing will bead it up, and I can't imagine how the nozzle would actually have any effect on it once it hits the car.
The only difference would be that it's a flood pattern, instead of a finer spray. Which you can do by just not using a nozzle. And at the end of it, if there aren't enough slopes for that water to cascade off of, it will remain on the car, and still give you water spots. Just so much easier to use whatever is comfortable, and towel it off afterwards. Or at the least, towel the hood, trunk, and roof. The vertical services are going to drain down faster anyway, but the horizontal is where I notice it as much.
EDIT: just read some reviews on Amazon. So for spot-free, you're basically doing exactly that: Taking the nozzle off. (clicks apart instead of removing from the hose). Sure it might be nice if you need a new nozzle anyway, but I wouldn't go out of my way to replace one with it.