hi, i cannot give you any information on the engine, i can however give my opinion on the tires. Despite the slimmer tires on the people, they are safer if you encounter road imperfections. The larger diameter will prevent the tire from sinking as low into potholes, holes, cracks, etc... as a smaller tire. I used my people in NYC a lot where the potholes sometimes are 6 to 8 inches deep and i have never had a problem (omitting a sore rear end). I know a few people who have been thrown off when the smaller diameter tire dug into this sort of imperfection.
I don't know much about the contact surface of the tire, but i do not think that the smaller fatter tires have much more of a contact surface area (i might be wrong, i am not a tire expert).
I have been riding my People 50 2t for over 1 year and 1/2 now in many many conditions (including snow :O) and i have never had a problem linked to the tires. The rim is very heavy duty, i think since people are not used to seeing this skinny a tire on scooters they sometimes assume that they are much less safe.
In any event, good luck, and happy riding.