or if you can afford to buy a Mac server, lol... hum, ok, not everybody can... but on my side, each big site like yours is having its own xServe in my rack... no need of a panel... OS-X is managing everything better, with a complete interface (like in your computer or so)... and is faster and easier to manage once you started to manage users accounts in your own computer, that's the exact same thing...

it all depend on what you have to do with your server... on my side, i have 9 or so clients with forums with more than 500k users, so i have to have a monster... i prefer that way instead of hosting on commercial places.. just need a T1 or better... one is sharing live feed and video chats, so we need something that will handle the content, not only the downloads...