Well, I have a 5g reef tank with 12 years experience. Big tanks take a lot of money for lighting and equipment. They also take a lot of money to fill up with corals if you are impatient for them to grow in. A 40g breeder tank is a perfect starting size for corals. It's just big enough not to be considered a nano tank and enough gallons where the water chemistry doesn't change as rapidly. It's also small enough to not take up a lot of money setting it up - because of the lighting, pumps, skimmer and filter.
There are both advantages and disadvantages of going either big or going small - depends on your level of skill. Personally, my judgement is that you have been in the hobby for a while and obviously know how to keep fish and inverts alive, Why not try to keep a smaller coral tank, like a 40g breeder?
