It doesn't perform any differently, although many people consider the old stuff to be more uniform in character. As with all things, natural or unnatural, it's about aesthetics, and rarity. From a "performance" standpoint, it's just paper micarta.
As far as the color change, it goes from an ivory color (look at the end shot of the insides of the scales) and eventually turns a light butterscotch color. If you're careful with shaping, you can maintain some of that color when you shape the handles, at which point you'll end up with a bit of a "sunset" effect, that'll deepen over time.
FWIW, much real ivory has the same effect, yellowing over time. Some older collectors that have been around since the days that this material was plentiful, still consider anything micarta to be junk, and don't find the color change endearing. From my perspective as a maker, I enjoy the complexities of it, the idea that I can consider those changes as the ultimate vision of my work's aesthetic. Does it make a better knife? No, very little if any embellishment does.
It's up to each of us to decide whether changes in the character of a piece over time adds, or detracts from value. For me, the answer is simple.