I've got EC90 SLX forks on two bikes purchased in 2006 and they both have "nanotube" decals on them.
Concerning the newer interior threaded steerers, my two forks came with Easton's "Beartrap" expandable spacer to adjust the headset and came with no expander plugs. The Beartrap was a dismal failure and I have FSA expanders in both and they work fine. Easton admitted the Beartraps didn't work and sent me the expanders gratis. I assume the threaded steerer interior system works a lot better.
As to "flexy", mine certainly aren't but then I'm 150 pounds.