The only reason I upgraded from my D70s to a D300 was the vastly superior noise handling of the D300. It has been a painful upgrade though, I had to sell two fine lenses to afford it, but the benefits should be clear when I hit the Edinburgh Festival at the end of the month.
Had I not got aspirations to earn some cash from photography, the D70s would still be fine for my needs. In fact, it's still a dman fine camera now.