on a large tank they are definately worth consideration.
the only drawback that some sumps have is offgassing CO2 in a planted tank..but many designs can be sealed and reduce the loss..those where the bio media and filter floss are in a sort of seperate secion where you can seal the unit.
Mine is drilled..but there are continuous siphon over flows too.(these hang on the rim ff the tank..there is one box that hangs in the tank and another on the other side where the water drains..