I wouldn't worry about how long you can ride the scooter. Just keep the oil level checked and you should be OK.
As with any engine, the more it is operated, the more it will wear. That's just the facts. A bigger engine will not have to work as hard to maintain speed, but still has the same moving parts.
I have an Agility 125, and I wouldn't hesitate to take it out for a day ride. I have a couple of motorcycles at my disposal that would be a much better choice. I use my scooter for commuting 13 miles to work and 13 miles home and running around the paddock at track days. If I'm going to go long distance, I grab a motorcycle.