Something to be aware of since you're already a motorcyclist- Scooter maintenance needs seem to occur with more frequency than cycles. I'm not talking reliability, but rather service intervals and replacement of wear out parts- Tires is the biggest one.
Small scooter tires are always a topic of discussion. Next big maintenance point- drive belts; typical replacement in the 6-12k range. Drive pulley sliders are another thing which get lots of focus as well. None of these are high dollar items mind you, but they do require service, and therefore can be a problem for high mile riders. Oil changes/valve adjustments depending on model can be a frequent concern.
Not trying to put you off on scooters- they are great, but if you like to do big miles on your bikes, you should just be aware of some of the differences that you'll find coming from a motorcycle background....