UPDATE: I talked to Kitchenaid after receiving an e-mail with the factory phone number. They say that both the 7 and 8 qt models use the same motor, etc. The 7 qt is rated for 16 cups of flour, but the rep said that is based more on the motor than the bowl size. The 8 qt. saying it is rated for 14 cups flour is a TYPO they believe, but haven't heard what the correct number should be. Since it is based on the motor size, she said to assume it also should be rated for 16 cups.
She also said the bowl is only taller, not wider, and uses the same implements as the 7 qt. I didn't think to ask her, but I wonder if you could use the 8 qt bowl on the 7 qt model?? She also said the 8 qt comes in more colors than the 7 qt.
Does that make anyone's decision easier? I think a taller bowl would help contain more dry ingredients in the bowl. I am waiting a few weeks to see if more reviews pop up on the 8 qt. One finally posted yesterday to the kitchenaid site - a person bought 2 mixers, one is working great, and they had to send the other back for replacement due to a clunking noise. They were happy with the one that was working, though.