I also come from the North East of Scotland and as far as I'm aware everyone I know would say the kilt is their national dress as well. I also know men who don't wear the kilt but would say it was their national dress.

My father also wore a kilt, my relatives wear kilts, my friends all wear kilts and that's not including piping friends or members or ex-members of the regimental association. I grew up with kilt wearing men around, but we were a Gordon Highlanders family despite having the Black Watch billeted with us one summer.

As far as I am aware the kilt has been considered an item of Scottish national dress, (not just the Highlands), since at least the mid 1800's, mainly due to the high profile given the kilt during the 1822 visit of King George IV to Scotland. Scottish troops have taken the kilt all over the world since the 1700's and many thousands of them died in their kilts during WW1.

If you attend an international rugby, or better still, a football (soccer) match and see the Tartan Army you will get a rapid answer as to how the kilt is percieved as a modern item of national identity. For better or worse, you will see thousands of kilted Scotsmen in the space of a few minutes.