I just got back from my second trip from the LA Auto Show...
The load limit for the Pure is 518 pounds, 235kg.
The load limit for the Passion is 507 pounds, 230kg.
The load limit for the Cabriolet is 463 pounds, 210kg.
My guess is, that as additional equipment is added, the weight of the equipment is factored in and the Load Limit for People & Cargo is reduced.
As far as overloading beyond the limit, the people in the Smart booth said that the extra weight exceeds the suspension system's design, puts extra stress on the tires, will reduce the MPG, and is NOT a good idea. After all, every car has a limit as to what it can carry.
Best Wishes,
Bob Diaz