My 22-580 used to plug using a 1 hp Penn State one bagger unit, but since I went to a 2 hp Oneida cyclone, no problems. It uses a 5" vertical from the 4" short hose then goes to a 7" main, so it gets a lot of suckability.
The discussion of 4" being too small and 6" being too large for a unit like the 22-580 is exactly why I went with metal duct so I can go in 1" increments.
Another item that helps is that I went to the 4" clear expandable Dust Right hose from Rockler. Using it with the 22-580, it sucks down to about 18" long to minimise losses.