My S150 will do 60 with me on it alone (210#). That feels pretty fast, actually very fast. Nevertheless, the scooters, probably due to a low center of gravity, are very stable, and not "twitchy" at all. I ride up a gravel hill to get home with no problem.
You will never be as safe on a scooter as in a car, as I am sure you know. It is no more dangerous than a bicycle, except for the higher speeds. Bear in mind that many millions of people all over the world ride them. You can keep your danger to a minimum by being smart and avoiding any dicey situations. Only you know if you are that kind of person. If you aren't, get a car.
With regard to the stock seat, it is fine for one, pretty awful for two. I got the two person seat, and my wife says it is plenty comfy. I have a topcase with back pad ordered- I suspect that will make her feel more secure and comfortable.
⚠️ Last edited by shankhill on UTC; edited 1 time