Silent_Scope: No, my system is not older than yours or Neosnetsh's. The age of the systems coming off the manufacturing line is measured, I think, just by serial number. All three of our systems would be considered very old, "first generation" Neo cart systems. There were, I think, at least three generations of Neo cart systems, each with different motherboard and/or daughterboard configurations (first gen had no daughterboards). Anyway, Jeff Kurtz is the best source for information about the various different Neo cart system revisions, I don't really have that info.
I will say that many people say the newest Neo cart systems, with serial numbers above 300,000 (format 3xxxxx) are supposed to have the best video output. I've never seen this with my own eyes, but I did have my Neo cart system modded by Jeff Kurtz for s-video output, and the picture looks GREAT!!!