I have always been an 'available light' photographer but would now like to add a flash gun to my kit to improve my low light photography. Its main use would be at weddings and family type gatherings where it would be possible to bounce flash off ceilings etc It would be used with an eos 350d and my new 40d. At a recent wedding the professional picture taker was using a 5d with a 550ex fitted to the hot shoe which while it seemed to be very versatile it looked as though the cameras handling was affected by the size of flash gun. I dont know much about the latest units but I understand they can 'talk' to the camera and would it be best to stick to canon? any advice/recommendations gladly welcome!