The 20D, and other like Canon cameras, have a shim between the focusing screen and the screen or base above it. There are 10+ different thickneesess. While many of the shims are the same thickness (I don't remember what it is), they can vary based on the exact needs of the individual camera....think kind of like a bell curve.
Unfortunately the Haoda screen is designed to not use the sceen and assumes the most common thickness. If you fall outside that (either way) you cna/will have focus problems.
The focusing screen I decided on was the Katz Eye Plus Hi-Lux screen ( http://www.keoptics.com/Canon20D.htm
). It is a horz. split (not diag) with dimentions and tabs exactly like the Canon....and uses the existing Canon shim, so there are no focal changes. Plus the image is much brighter, which is really noticeable with zooms having variable maximum aperatures, particularly up in the 5.6 range.
John