My very unscientific analysis of scooter numbers today, riding around NE Portland, is there were about as many scooters as bikes. They seem immensely popular to me, with users ranging from adolescents to office workers. I don't know what their speed limit is, but I'd guess far faster than 7 mph. We'll see what happens once the rain starts.
I see them all the way out in Gresham, 10 miles from downtown Portland. I don't know if they were ridden out here, carried on the Max, or seeded here. But they are being used.
My guess is, scooters are super easy to rent and ride. Quicker than walking, too.