Drilled or External Overflow?

[Reefpins10]

I just ordered an overflow box from Lifereef after I read this useful advise for not using a reefready tank.

http://www.aquacorals.com/ShopAquariums.htm

[trilinearmipmap]

I have never used a hang-on overflow but if I did, I'd get a lifereef, and also add a float switch so my controller would turn off the return pump in the event of a siphon break.