Regarding the Dynax 9, it is indeed pretty well bullet-proof due to using a stainless steel body, and although the AF is not as fast as say, that of Canon lenses, the focussing at low light levels, was very accurate. The only 'niggles' I have with mine, is the DOF button (like many other camera manufacturers!) does not protrude a lot above the body-shell, (Annoying if you are using gloves) but I've already found a way of resolving that, by adding a bit of plastic to the face of the button. I much prefer it's 'traditional' controls and the weight, helps a lot when it come to holding the camera steady on slow shutter speeds. Some say it looks 'Ugly', but what do you really want, a functionally and ergonomically designed body, or 'Status Bling'? Regarding the upgrade, does it really make sense to put optics optimised for the APS-C sensor, on a FF body? Undoubtedly the Zeiss optics are going to be good, I doubt if they are that much better. Rokkors had a reputation for 'Contrasty' and optics, something that gives really good colours on film and digital sensors.