Pros/Cons of external (builtin) overflow

[Delphinus]

I'm trying to decide on whether to spec out a tank with an external overflow box as opposed to the more traditional internal box.

This is how I see it so far:

pro: you retain the all the original tank volume as usable for aquascaping. May be more aesthetic.

con: The glass needs to be notched out, potentially weakening it. Also you have only one water overflow edge, as opposed to three edges, thus the potential for blockage is increased.

Another con is that it complicates how to move the tank (unless the box is retrofitted after the tank is in place).

I had originally wanted to go with the external, but the tank builder has almost talked me out of it .... can someone talk me into it?