After spending well over a year trying to play FFX and FFX-2 on a PlayStation 2 emulator, I decided to go back to the roots and play it on my PS2. Never before have I actually noticed a difference between the quality you get from the Analog (RGB) cables versus the quality of the digital signal. My mouth literally dropped at the difference. I've had these component cables for a while, so you'd wonder why I hadn't noticed it earlier. The digital feed looks virtually identical to what you'd see on a PS2 emulator: sharp edges, bright (and accurate) colours, no fuzz. Even the subtitles/text looks sharp and crisp, instead of slightly blurry around the edges. Of course, this was all taken in on an HDTV, so I'm pretty sure there isn't much difference between the two cables if you're on a standard definition TV.
The only drawback I can see, are vertical 'bands' of colour across the image. It only happens during gameplay sequences, the CG movies are unaffected. The stock cables, although the image is not as bright, or sharp, the transition between colours is much more smooth.
I just thought I'd share my two-cents for all to decide whether it's relevant to them or not.