Down here in the south, those reflective white signs with the big black numbers are there to tell the nearly-illiterate, self-centered cagers the minimum they should be traveling. They're not an upper limit as the sign actually indicates, but the floor-speed at which someone should be traveling else they get run over, have things thrown at them, get shot at, or otherwise suffer induced-wrath things from idiots who want to punish everyone else for their own poor time-management skills.
I was perfectly satisfied with the 153cc of the Honda, until I realized that I was the only one who thought those big white signs with the big black numbers really were an upper limit, not the base floor speed of travel. You literally can get a ticket for both reckless driving and impeding the flow of traffic (both misdemeanors, but when combined are a low-level felony here) if you're driving while obeying traffic laws, operating safely, and doing nothing other than being in the way of soccer moms in their black Denali SUVs while on the phone.
Given the roads I have to drive in order to get to work, something with a bit more "get up and go" eventually became a dire necessity. Not to mention the fact that if I ever wanted to go anywhere other than to work, I'd need to be able to travel in the 60-75 range in order to do it, without running the risk of being run off the road.
A case in point: (and possibly for the Riders Code thread) yesterday, on the way to visit a friend of mine to meet for lunch, I was traveling on a 55mph limit road, but going right at 63-64mph. Not one, but two sets of rednecks in jacked-up trucks with 6' diameter tires flew by me at over 80mph estimated, screaming out the window "get that &%@#! moped off the roads" The second of the two cut over in front of me so sharply that I literally reached out and touched his fender as he swept by. I immediately changed lanes, as I anticipated he would slam on brakes, which he did. I went right on by as he nearly came to a stop, and then he had to try to catch up to me to show me who was boss. I managed to skirt through a changing traffic light, where he was just too far back to not run the red, and I left him sitting there stopped and probably fuming that I was a lot faster than he thought I was.
So yes, I do need more than 150cc. And pepper spray.