Yeah, good thing the clean water stays on one side of the tank and the dirty water keeps to itself on the other side of the tank.
I should say that you could use a drip system but in order to keep the water clean for discus, you would want a pretty consistent and continuous flow. Plus, you need to calculate exactly how much you are actually gaining from the drip system. A 4g drip an hour into the tank does not mean you are changing 4g an hour. Yes, the water will be cleaner than doing nothing but I still think the overall consensus is that large w/c's beat drips. You get an instant clean tank of water. This is more important when growing babies or juvies. Nitrates are a good measure...If they are low, then you are probably doing ok.