First off, it's shutter lag, not shutter lack ....
Brutal: Hey, Jonathan you've got to start answering these questions AFTER that first cup of coffee in the morning and not before ...
But back to the question, if you shoot ISO 3200 on the 20D you'll want to include a copy of Neat Image, Noise Ninja or Dfine in the budget to clean up the images. Using these, or the more sophisticated noise reduction techniques in PS, you'll get images that are very acceptable for the lighting conditions. The good news is that the 20D doesn't get all blotchy with high ISO noise.
As Jonathan says, the shutter lag is minimal and certainly no worse than any other film SLR.