I can see a clear improvement in quality between S-Video and Component on a 480i CRT. In fact, it's a really big leap in visual quality, just like S-Video was to Composite.
If available, use it even if we're not talking about 480p or HD games.
I regularly play several pre NES consoles like my Colecovision with component video after modifications, and you even see a vast improvement on those.
Wish I had them still, but I took pictures of an episode of I Love Lucy on DVD a while back via composite, s-video, and component on a 480i CRT for a classic tv/movie forum I visit and there was a clear jump in quality. It completely got rid of the rainbow effect you often get from patterns on clothing for example, where as it was still somewhat there on the s-video shot.