Reef Ready tank vs Overflow Box?

[95harley]

So I'm shopping for a new tank and I have a technical question.
I have a 240g and a 75g both with built in Overflows (Reef Ready).
I also have a 180g with a Continous Siphon Overflow box on the back.
All three running Wet/Dry's.
So my question is if a RR tank takes up inside space in your tank, what makes it any better/worse than an Overflow hang on box?

 

[chilwil84]

they are not near as likely to fail and cause a flood. they also take in some water from lower levels in your tank thus giving a little more flow in the lower area

 

[natclanwy]

Reef ready tanks are less likely to have failure with the overflow, plus you don't have to worry about the size of your return pump. With a HOB overflow you return pump needs to be 70-100% of the overflows rating after headloss is subtracted, with a reef ready tank your return can be anywhere from 0-100% of the overflows rating.