I'm pretty stoked to get my hands on the Sun and Moon Demo. I actually never played the OR/AS demo (because I didn't follow the game during it's pre-release), but from what I heard about the exclusivity of a special item and transference over to the actual game, makes me even more interested in checking out the demo when it is released.
As for the "Data Mining", I don't really want to be spoiled on anything except for what the official TPC reveals have given us, so that means if the demo is data mined and the whole game is revealed or even just some important pieces that give away too much information, then I personally will go way out of my way to avoid and ignore any leaks.
I'm not going to blame leakers, hackers or even TPC for the spoiling of the games information. No matter what happens, these games will be hacked in one way or another, and information will be leaked. If I want to truly enjoy the mystery of playing these new games, then it's up to me to have the self control to actively avoid or ignore any leaks or reveals. Honestly my plan when Su/Mo is released I'm planning to actively stay away from most of the pokemon websites I go on to as well as I will purposely be avoiding the Su/Mo board and a few other of the boards on here.
I can't stop the leaks, but I can definitely prevent them from ruining my own game experience, just need to have a little bit of will power.