The last question is the easiest to answer.

Do you think its worth it? It will be you putting the cash (lots) in and the time (even more).

There is no more beautiful setup for fish than a well planned and mature marine tank.

As to the Orca's...i have read that they are very good. The thing to remember about the "all in ones" is they they tend to be built to a budget, barely any of them are actually suitable in their original condition.

You will almost certainly need to uprate the powerhead (flow is king in marines), are there are whole threads devoted to modifying the various makes of nano to the required specifications.

Not that any of the above is complicated (generally..lol).


General rules of thumb to conisider...

Bigger is better. More water volume=more stable conditions (things can go badly wrong in nanos very quickly).

Expect to pay lots of money...the set up may be cheap (ish), but assuming that you are buying the R/O water then expect to pay about 10p per litre. The salt mix isn't overly cheap.

All these little costs build up.

On the plus side, many corals don't need the expensive metal halide lights... so you can have corals relatively cheaply. Fish permitting.