Brakes are a must IMO for three reasons.

1. Max speed on straights requires braking prior to next turn.
2. Tight turns with MT class trucks sometimes require a trail brake style to turn faster/tighter.
3. Braking in the air for attitude correction for landing.

Proper braking is critical, especially for situation #1, where too much brakes can cause a spinout.

I guess the only other thing I would add, is that the track isn't as "groomed" as it looks in pictures.