Wouldn’t all the water drain out?

Depends on your budget and long term brewing plans. I was very happy with a MegaPot and DarkStar burner for many years. Then I got some Keggles and a second hand Edelmetal burner. Now I have a Ruby Street single tier gas setup. I plan on upgrading to electric this year.

If I was doing it again, I’d seriously consider going with a all-in one like the grainfather / brewzilla / etc.