In Brazil, we like the rodízio —where portions are constantly served by waiters. We have taken it everywhere, from the steakhouse to the pizza place. Nowadays, it's the Japanese who predominate in the "as much as you can eat" system. I suspect that, in contrast to their predecessors, the success of the Japanese has more to do with variety than with quantity.
Choosing food that we aren't familiar with can be intimidating, whereas with small portions we get a chance to try new flavors without feeling pressured.
And in this the two venues excel, serving unusual combinations —such as sushi flambé in orange liqueur at Mori or salmon and pineapple sushi at Aoyama.
Of course, the trendy atmosphere in both restaurants, filled with beautiful people, also contributes to their success.