Hey i have a slightly smaller cichlid tank and I have an Aquaone on it And it does a great job! And they are nice and quite. The good thing about a canister is that it doesnt take up room and look ugly inside the tank. I put my AquaOnes spray bar up near the top and find that it provides heaps of circulation and areation. I also run an aquaone in my community tank and actually had a problem with the circulation being so much it was uprootiing my plants, but thats all sorted now.
I have Mbunas and Haps together, I got them all as babies and at the same time and have no problems, so i guess it can depend on the fish.
Next you start thinking about substrate and PH buffers!
Good Luck thay are great fun