I agree with this.
The 20D was the dawn of a new era for EOS digital bodies. It had the 9 point AF system with an excellent centre point that worked in just about any condition, very short shutter lag, short viewfinder blackout, instant power on and awake from sleep, instant image review, easy to scroll around and change settings with the joystick nub, ETTL-2 rather than ETTL, and 8 megapixels which is enough to print nicely at pretty much any size you want.
I loved my 10D, but the 20D was really a huge step up. I could still be shooting weddings with a 20D and be happy. I mostly use a 40D now for almost everything I shoot. Great lenses are more of a factor IMO. Full Frame is definitely not necessary to do an excellent job at wedding shooting. I was still busting out my 20D at $10,000 weddings last year. I sold it and kinda regret it. But a 40D took it's place and wow, I find the 40D so good that I really feel like I don't need anything else to shoot a wedding. I have other bodies at my disposal but the 40D definitely takes the huge brunt of the work.
But the 20D is an excellent wedding camera. It was awesome back in 2005, and I'd be totally happy with it today too.