>Can anyone recommend a heavy-duty mixer? This morning when I was
>mixing a new SD recipe,

I have a K-Tech mixer and I use it almost every day. It mixes up six
pounds of dough without any problem. It probably will do more, but I
leave my dough in the bowl to rise so I have it half empty for that
purpose. I make three 2 pound loaves each time I use it. I never take
more than five minutes to mix. I love my mixer, and would rather use
that then knead by hand.It is so quick and easy for me. I have
directions for using the mixer with sourdough breads at:
http://www.northwestsourdough.com/techniques.html if you would like to
see what I do for mixing sourdoughs.
Have a great day,
Teresa