I shoot weddings and bar mitzvahs with a 5D and a 40D. I've never had complaints about the shutter noise of my cameras until about 2 months ago. I photographed a wedding and a bar mitzvah where the priest and the rabbi (respectively) complained about the noise of my 5D (clicking of the shutter and mirror slap). This Saturday I was stuck in the back of the church next to the videographer and he complained that my 40D shutter noise interfears with his audio recording. Since I cannot justify buying a digital rangefinder, I was thinking about picking up a Canon Rebel XSi (450D) - I heard that they are much quieter than their bigger brothers. Has anyone used 450D for professional wedding work? How's low light performance?