I have both HDMI and component hooked up to my Panasonic CRT-RP. I ran only component for about a year, and had to readjust all of my settings for HDMI. After doing this I perceived the HDMI connection to be sharper, with better color saturation.
I then used only HDMI for 5 months. But on a whim, I switched back to component and reoptimized. Ran that for the last 6 weeks until tonight when I switched back and had to reconfigure again. Once again, I perceive HDMI to be sharper with better color. Probably won't go back to component unless my HDMI connector fails - as it does on about 60% of all 622s.