I have a ~10-year-old KitchenAid Ultra power (300-watt) mixer. I have noticed that recently it seems more bogged down when kneading bread dough and mixing thicker cookie doughs. I have toyed with the idea for a while of upgrading to a new mixer, but looking at the options I am getting more confused as to which mixer is the best option for me. I generally use my mixer for thicker doughs and rarely use speeds higher than 6. If I go with the Artisan, I'm not sure it's a big enough power and capacity gain to make it worth the risk of getting a new machine (my current one isn't perfect, but at least I know its flaws.) At the same time, I'm not sure about the Pro 600 because of the price difference, plus it seems to have quite a few negative reviews compared to the Artisan. I'd love any input and advice! TIA!