I've heard the same things as you--I'd be interested to know for sure but I always go with the middle of the road "moderation" I read somewhere that if you do have a drink, to have it just after baby has nursed so that's the longest time before baby nurses again.
When I have had 2 wine coolers (for Heaven's sake--I'm such a lightweight after not having drank for nearly a year), I had such a letdown---the boobs just kept running!! That kinda turned me off of the drinks for awhile. But on occasion I have a wine or a mixed drink with dinner and that's it. Otherwise I pump & dump just to be safe.