The kitchen aid is the best dang piece of equipment in my kitchen short of my stove. It sure isn't cheap to purchase but I will never go without one again.
The grinder attachment works OK. It is great for peices of meat that do not have much connective tissue. Like chicken or well trimmed red meat, veggies for whatever (soups, risotto, meatballs, etc). But if you are looking to grind up boned out pork butts to make sausage.... you are better off with hand crank than this. Which I use and change plates to a smaller one and run it through again. For a 8lb batch it is faster, really. Large batches of venison get the big dog meat grinder.
The pasta roller attachment is outstanding. Makes the process of homemade pasta so fast and easy, you'll be filling sweet potato and ricotta ravioli in no time flat. Browned sage butter as your sauce to go with that, fyi. Try it.
The pasta extruder is total crap, don't waste your money on it. It is a hook up for the grinder attachment. I have tried just about every style of pasta dough I can come up with and NOTHING works well in it. They do make several sheet cutters to get spagetti or fetuccini. Now those are also OUTSTANDING. Looks just like the pasta roller but it has different cutting rollers obviously
As far as a dough mixer it is also great, all pending on your dough recipe. If you use a tough stiff dough I would do it by hand. I like a chewy stretching dough so the mixer hook works perfect for that looser dough. Almost a Strudel dough, just with some yeast.
I highly recommend it if you do a lot of cooking at home. I never needed it for mixing rubs but it would work equally as well. I know that neither the whisk or paddle attachment works very well for making brown sugar. It is just easier to do that by hand. (white sugar and molasses).
Hope this helps.