Dave,
First of all let me tell you I love my KitchenAid Professional 600 model. At the time I bought it there was a corporate promo that allowed me to get their meat grinder attachment for free – supposedly a $50 value at the time. I use it to grind my own chuck roasts for chili and it works fine. You just need to chunk your raw meat and then stick it in the freezer for 1 to 2 hours. It grinds much better that way. There are two plates – a fine and a coarse – the fine practically purees the meat and I don’t like that, but the coarse plate is perfect. I have never choked my grinder but then it is a powerful unit anyway. As for the stuffer attachment which I do not have I have heard mixed opinions. I recall the consensus is for the occasional home stuffer it is fine, but if you plan to be a heavy user than bite the bullet and spend the big bucks for a quality grinder and stuffer.
Ron