The only drawback to using a rack that I find is the room temperature. If you don't have a designated snake room where you can regulate the room temp it tends to be hard to keep temps steady in a rack. I have mostly cages but I am running one rack right now in my house so I have had to keep my whole house temp at 75 degrees all winter in order to have any hopes of maintaining my temps in the rack.
Other than that, I love the convenience of a rack system.