I'm also an Ambassador btw.No it was way before NNID existed, there was a price drop and those customers who had purchased before were rewarded with them, I believe.
Isn't Ambassador related to eshop, and Nintedo only know if bought 3ds before price drop if you went into eshop before price drop. and to go into e-shop, you need a NNID?
You only bought digital games?What does that mean? I currently at 10.7.0-32U and i don't own any 3ds cartridge, will I need buy one?
Also, that quote you had said DS and flash cart also worked.