Pros/Cons of external (builtin) overflow

[muck]

My tank has a overflow box built on the inside of tank. If I would do it again it would be an external overflow. Here is a few of my reasons.

- Blocks some of the light for the corals. Thus I can't put corals underneath it.
- Takes up more space in the tank than I really like.
- External overflows always look cleaner and neater while viewing the tank.

EDIT: Actually more or less the same reasons as Marc.