With 90 gallons you can get away with less water changes or even no water changes. IMO, big tanks are easier to maintain because you have a sump for more equipments. It is way more expensive though....i have a 90 and water changes are a PITA i would just replace some coral i have just bought a fluval evo 13.5 and only going to buy £400+ corals
this will be my 1st coral