As for growing a bigger plant, I doubt it. Not autos anyway. But I do agree the bigger the res the more stability you'll have. Just because the the container holds 20 gallons don't mean you will using 20 gallons of nutrients. Who puts 5 gallons in a 5 gallon bucket? Res changes can be made easy, add a water level gauge or drain ball valve, hook it up to a water pump and pump it out. Never will have to lift the netpot and plant out.