Not saying 12" wheels are death traps - just saying that after swapping back and forth between two 260lb, 150cc scooters, for 2 straight years, I've noticed a pleasant difference with a 16" wheel.
You probably would, too, if you test rode them back-to-back.
(I do read that Europeans vastly favor a big wheeled scooter over any with a 10 or 12" wheel)
Stig