Hi Carolyn,
I bought a KitchenAid KSM90 earlier this year and have made bread in it 3
times so far. I used it when I wanted to make an amount of bread that
wouldn't fit in the ABM! Each time it kneaded very well - no straining the
motor at all. I've used up to about 6 cups of flour. The manual says not
to use more than 8 cups of all-purpose or 6 cups of wholewheat flour. The
dough does tend to want to rise up the dough hook (past the large flat part
at the top which, presumably, is supposed to stop this happening), so you
have to keep an eye on it. The bread turned out well.
By the way, I think mine is a European model (why, I don't know, because I'm
in Australia), so the model number where you are might be different. There
was a more powerful, professional model (read: more expensive) available,
too.
Jo.