Besides flow rate, it doesn't serve the same purpose as an overflow. An overflow is meant to take the top layer of filth out of the water column. It does this by allowing the water to overflow into a separate section. From here the water is sucked out at a reasonable rate because it is below the water level. Also, the water level in the overflow section is higher than the pipe to allow full pipe diameter water flow. Water will flow back in at the same rate it is taken out. Because of this, it has its own siphon break.
The only way that I can see to get a good flow rate out of that setup is to plug the siphon break and connect it to a sealed filter to prevent overflow. If you don't want to see the overflow, there are other options. They make overflow guards that go from the top to bottom of the tank to hides the pipes. If you have a colored or design background, you can create or buy an overflow box and have it match the background. If you do that and put it in the corner, it will be practically invisible.
Another option would be to make the siphon break tube a little taller and putting a bubbler in the tube. This would help to increase the amount of water that flows over to the other side. It will also oxygenate the water while allowing a place for the air to escape to prevent a constant siphon break. This is the same concept used in "automatic/self-priming" overflow boxes that hang over the side.