I was also wondering if you could do game server hosting for Terraria. I just recently switched to from Xenon Servers' Terraria hosting to a VDS on your servers so that I could have more control over plugins and server files. Right now I have a 30-slot server running on Windows Server 2003 (I believe that Xenon also used Windows Server 2003 for hosting, with TCAdmin) and it runs great. I did notice a slight performance drop when loading the server (used to take 30 seconds on Xenon, now it takes 4 minutes, probably because it spikes the CPU usage to 100%) but there is no performance drop whatsoever in gameplay, it might of even improved.
When the server is running normally, it uses less than 10% CPU (and this is on the lowest VDS plan, 1 HT Core) and uses about 200MB of RAM for the process, 700MB for the entire server including other servers and the OS.
Also, Terraria allows for these settings to be set on start through the command line:
-ip <ipv4> - Starts the server bound to a given IPv4 address
-port <port> - Starts the server bound to a given port
-maxplayers <count> - Starts the server with a given player count
-world <file.wld> - Starts the server and immediately loads a given world file
-worldpath <path> - Starts the server and changes the world path to a given path
-autocreate <1/2/3> - Starts the server and, if a world file isn't found, automatically create the world file with a given size, 1-3, 1 being small.
-config <file> - Starts the server with a given config file
If you have any questions about my server setup feel free to ask.