We just came from Breck. About a 1/3 of us were hit with altitude sickness (including me) which means splitting headaches and weird body aches. Advil helped for a minute, then a small beer, then it would come back.
2/3 of us (18 total) drank no problem. They were pounding the beer/jameson/cordon bleu/wine. This was with a little acclimation. Denver Friday night, Breck Saturday, Drinking saturday night at the village/cabin. I don't give a shit what studies say, one beer even at Denver elevation was noticeably more potent. I'm taking a damn good buzz after one beer when I could probably do 2-3 to feel the same here at sea level.
But those other fools were pounding drinks and no complaints the next day on the slopes. They did get that full saturday to acclimate I guess.