Two problems re alcohol and running are the dehydration factor and the fact that alcohol stops your body absorbing the vitamins and minerals from your food, which will obviously not help with recovery.
The safe limits, like many things, depends a lot on your individual body, so if I were to drink the same as a 20 stone man, it would have much more of an effect on me than on him, both at the time in terms of intoxication, and in the aftermath in terms of the liver's ability to process and dispel the alcohol and the absorption of vitamins.
I rarely drink at all these days (for various reasons) and feel so much healthier than when I drank (although I didn't run then). My consumption has never been huge, but there was a day when I would be out 4 nights a week and knock back a few each night. Now it's a couple of glasses of wine about once a month. I don't miss it at all.