BUT it will hold them back, or don't you understand. His recent posts were great, some wicked photos in situations where he is able to greatly control the lighting of every entire scene to the point where you could use a P&S camera and get great results. However life is not about being able to control and manipulate lighting perfectly in every single picture.
The d90 has 50% more megapixels, a substantially better AF system, a bigger LCD, way better ISO capabilities, better in camera metering, better build quality, heck the list can go on and on and on. I can see how the camera is worth the money with this alone.
The sales staff in most stores try to give you an unbiased opinion which is something you aren't giving him here. If sales staff were so over the top biased they'd be telling people to buy Sony instead of Nikon since many of the cameras share the same sensors. Oddly you rarely see them doing this.
Right now more than anything you just scream of a Canon fanboi. There is seriously no reasonable means to recommend a 20D over a D90. Not to mention there is no single way of verifying how many actuations are on that 20D.