I do not believe you have kept this tank long enough to even consider it a success. And I do believe, that fish are fish, and in close quarters eventually they will become stressed, and problems will arise. I do not personally believe in keeping fish in crowded, unnatural population densities. I do not enjoy that personally. If you do, then so be it. Take praises about your tank and enjoy it....but it is not, IMO, anywhere near long enough to consider it a success. And even if that happens, it is a fine line. A fine balance, and probably many would fail for every "success." I don't consider it a success to keep fish in these conditions regardless. Success in this hobby is growth, normal behaviors, and even reproduction in certain fish. Success IMO is the best possible artificial recreation of a natural habitat, density, etc.
But this is not my tank. And it is not my decision in the end. If you are content with it then so be it and best of luck.