Hi Paulkai, IMO, it depends on the capacity of your bio filters. The larger your biomedia (lr, ls, filter media, etc), the more you can put in your tank. But make sure your reef tank is matured before adding any fish. Many, including myself, made the mistake of buying some fish 2 weeks after their initial cycle is over, and they all died over several weeks due to health problems. IMO, that simply is not enough time to ensure your fishes health. Things are still unstable in your tank for some time after the cycle. I would wait anywhere from 3-6 months after any changes where made to your tank before adding fish. BUt that is only my $0.02. And I bet there are some people out there who have had absolutely no problems with fish they bought right after the initial cycle.
And I don't know much about inverts, but it seems to me that they would also add to the bioload because they breathe O2, emitt CO2, and poop.
sam