Hi Cloudclipper & welcome to Pixalo
Being a Nikon man I'm gonna hand this over to the Canon guys. What I do know though is the 30D with its metal body is going to withstand the physical knocks from your pro work a lot better than the 350D or 400D. Also to note, if someone is paying you to take their wedding photos, they expect you to have a more expensive camera than their relatives, who could be there with their 350D, 400D's
