I think attaching it to an existing system would be great. I can't due to lack of space where my 200 gallon is in the house. Plus I am putting this tank in my computer room so I have something to look at while I am on my computer.
I have decided to get some Onyx Percs from Rod Buehler here on RC. I am still researching what my best option is for the anemone. I have had great success with anemones in the past so I think it is more a decision on what type would be suitable for the Percs, and the size of the aquarium they will be going in. I don't want this to outgrow my system like my Blue Haddoni did.
I don't think a 30 is too small for Maroons. I have seen ORA's setups for breeding clowns and they use very small tanks. The only thing I would worry about is the female maroon's aggresiveness toward the smaller male when first introduced.
I do think a gigantea will quickly outgrow a 30 gallon tank. They are very similar to haddoni's and I know haddoni's grow fast if fed properly and given good water conditions, flow, and lighting.
I have become extremely fascinated lately with specialized biotope environments, and I think this is my first step into that arena. I would love in the future to setup other tanks with the same idea in mind. Tanks for seahorses, pipefish, anglers, mantis shrimp, jellies, etc.