I've read a number of posts both here and on another forum about issues with KA's mixers. Namely they can't mix the large batches they claim to, overheating, and breaking down. I've heard the older ones made by hobart were much better mixers. I've read that Bosch mixers tend to have a long life.
I would save the $250 and put it into a bosch. Even if KA covers their mixers with warranties, it's a huge inconvenience to have to send something in for repair. I'm sure there are alot of happy KA owners but again, I have read about a number these issues. Which is enough to scare me away. If I were to buy a KA, it would be an older one from ebay.
Maybe folks with KA's can chime in. As far as a bosch mixer doing a better job of mixing than a KA. I'm not so sure about that.