Hi Joe:
I have had the Delta 50-760 for a while now, and I could not be happier with it. For it's size and HP rating it sucks big time!
There is only one thing I would add that may have not already been said. If you are planning to use it as a centralized collector, and you have any runs that are greater than 12 ft, I would advise setting up your main branches with 6" duct. Overall, you will lose less suction to static pressure and the velocity in the mains will be more than adequate to keep the heavy stuff moving.
After reading Sandor Nagyszalanczy's excellent book, I decided to run some simulation tests with my 50-760 (before I bought all of the ductwork, of course) using both a 4" and 6" main. The difference was dramatic with the 6" performing much better. My drops coming off the mains are all 4" which makes for a very straightforward design.
There is some more detailed information in an old thread I started a while ago.
http://www.sawmillcreek.org/showthread.php?t=63798
Good luck!