Like I said, even I have a tank with a single drain that has not had problems. Two of them actually. So I fully understand they can function for long periods of time without issue, but it does happen. Even with screens, they can get clogged with things growing in there and unless you keep up with regular maintenance as you said, you won't know it's clogged until it's too late.

Not to discredit piece of mind, but the biggest draw for me with bean is the noise. I've tried every method out there on a single drain, nothing can scientifically work the way a bean drain does; well, except a herbie which I believe is mainly a bean without a dry emergency and still a 2 drain system. You can muffle it (wonder where MM got their name?) or restrict the flow, but you can't silence it. On a bean, both drains work together to handle the flow and the noise. I seriously can't tell this tank is running. I'm not telling anyone what to do, I'm just sharing what has worked for me.