All of the Manfrotto quick release systems suffer from a major defect. They allow the camera to rotate on the quick release plate, this becomes a real issue when using longer lenses or fast heavy glass.
I'd suggest you have a close look at the "Arca Swiss" type quick release system (QR) which is the industry standard for QR's in professional photography.
Manufacturers such as Kirk Photo (
www.kirkphoto.com) or "Really Right Stuff" can supply not only the QR base but also a custom non rotating plate designed specifically for your cameras bodies. Plates for the 350D and 5D run around $55 USD each and the QR platforrm clamps range from $40 to $115 USD each depending on length. Shipping is via FedEx only though.
Cheers,
Ian