I believe a few years back there was actually a study showing that drinking alcohol while you roll actually increases the effects to a certain degree. I can definately agree with this, as when I rolled I always drank, especially after the comedown.
My only warning, is do NOT go overboard with it when you come down. I developed a serious problem with drinking when I rolled, making it necessary for me to stop rolling all together. At points, once I came down, I would drink non stop. Vodka would taste like water to me and I'd usually end up drinking at least a 1/5 everytime I rolled. Towards the end I would drink 1.75 liters of vodka or whiskey in the matter of a few hours. This provided me with some serious cases of alcohol poisoning, life threatening levels of dehydration, and a beat to shit liver and stomach. I am so glad I quit rolling.
Alcohol + MDMA is very very very hard on your liver as well, so don't do it often and try not to go overboard.