Most of the best sushi joints that I've been to use rice that is just
lightly warm much of the time. There is some variation in temperature,
and in density of packing, but generally I like it best when it is not
at maximum density but it still holds its shape long enough for me to
(god forbid) pick up a piece with chopsticks instead of my fingers.
The warmer temperature brings out more flavor from fattier cuts of fish
like toro and salmon.

Of course with maki, the looseness of the rice is less of an issue and
the warmth can reduce the crispness of the nori.

now i'm hungry again.