Here are some comments made in eGullet, Chef2Chef, and on ChefTalk site on the subject:
"I had heard our local Tim Healea say the same thing andiesenji said that they chew up the new KAs in the bakery but had an old workhorse with the Hobart inerds that lasted forever and his advice was the same to go on e-bay and buy an old one."
"If you can find one of the earlier KAs made by Hobart and refurbished, you will have a much better machine. I had one for 30 years that was a real workhorse. I bought one of the newer ones but promptly burnt out the motor mixing thick dough."
"As for new models vs. old, I'm generally of andiesenji's way of thinking. In the case of the KA mixer she, of course, has the anecdotal/empirical evidence to prove it. I can only say in general that those older and more solidly-built appliances seem to win the contest hands-down every time."
"Btw, are you sure you want a KA pro 6? I've been hearing very mixed review about the new mixers. The old ones are work horses - new ones, not so hot."
"I love both, but for home use, KA is great - esp. the Heavy Duty line. I have had one for years, and never had a problem. Hobart is well, Hobart. They are the #1 name when it comes to mixers. And for a reason."
"oh, and as far as kitchen aid goes: In my opinion the type of gearing is as important as wattage - stay away from the beltdriven models. The geared KA's are far better and longer lasting. Hobart - while more expensive - makes a much better mixer. "
" My KA Pro Mixer broke two weeks after I sold it and two weeks before the one year unconditional warranty expired. Williams Sonoma replaced it with a brand new one. When the owner turned it on, nothing happened. He returned it and WS replaced it again. No problem.
I replaced my KA Pro mixer with a Kenwood which has been running fine for the past two years without any problems. Makes me wonder why there's some many refurbished KA's on the market.
If my Kenwood mixer ever dies, then I'll opt for the Hobart 5 quart mixer. They can be found at ebay for around $4-600 slightly used."