I love my sump, it hides the heater, CO2 gear and allows a space for me to grow out some plants.
I have a 60 gallon sump, my tank is designed with a coast to coast (c2c)overflow and has three drain pipes (google beananimal setup). There is a siphon for the main line so no noise, no gasing off, I keep the three sump compartments about the same as far as water level (with room for the water that comes down before my air break kicks in when the pump goes off) so that also decreases gasing off. I feed the CO2 into a reactor that I have bio balls and porcelai.
If I had to do it again, I would do the same setup but with teeth on my c2c so little fish wouldn't end up in the overflow or sump as often. Or I would just make the tank bigger and run canisters, lol!