Mark, you mentioned the other day that you had a Kenmore Progressive vac. Would you tell us some more about it? Is it tough enough for everyday commercial work?

It seems there are 2 basic types of vacuum cleaners: those that vacuum well; and those that are designed and built primarily to stand up during the rigors of repeated jobs being performed by hired help who don't give a crap whether the thing breaks or not. The durable one is not very likely to also be the best at picking up stuff, especially pet hair. So, that being said, if you are doing your own work, and taking good care of your own equipment, I would go with the Kenmore Progressive. It is primarily a machine intended for use by people in their own homes.
On the other hand, if you have low-wage, poorly motivated employees doing the work for you, I would go with one of the dependably durable vacs, like the Sanitaire. It won't suck pet hair as well, but it will hold up longer.