My subjective experience is that alcohol can negate some of the 'magic' of psychedelics.
Never was much of a drinker though, so others might have a better answer for you.
I have had amazing potentiation at the tail-end of a 4-HO-DET trip, after smoking a joint with some really strong tobacco in it.
Gave me some amazing mandala CEVs. Quite beautiful.
But i have a very low tolerance to tobacco - and frankly i wouldn't recommend people smoke that crap.
It was an interesting experience though. Tobacco has beta carbolines in it, which are a mild MAOi.
Passionflower is another mild MAO inhibitor, which lacks the intoxicating (side?) effects of liquor.
I don't drink at all any more, but even if i did, i don't think i would mix alcohol with tryptamines.
Too muddying IMO.