I also have two KA's and LOVE them. My original tilt-back head mixer is at least 10 years old and while it seems to struggle a little bit during Christmas baking season, it bounces right back after i've let it rest a little :) My mom bought me a new one with the bowl lift from Craigslist a month ago and while I do like it quite a bit, I don't like that the paddle and whisk attachments do not reach the bottom of the bowl, which confuses me. (Yes, I have it raised up :) )
I do recommend KA though. They work VERY hard and get the job done.