I rode one for a few years, also comes in a 125. The flip up is required, because the filler cap is under there
I couldn't use it as a back rest because my legs are too long. It pushed my knees too far forward so they got in the way of the bars. (It was going to be ridden by someone with shorter legs when we bought it but she had an early get-off and didn't feel like getting back on it after her knee healed and so I used it instead.) It's a sweet scoot, though. Easy to derestrict, fun to ride.