yeah unfortunately alcohol seems to be my biggest vice when it comes to my ibs. I don't drink that much anymore because i know when i do i'll get pretty messed up. I'm usually okay at the time (on a night out etc), but the next day i pay for it. I'll usually have D and an upset stomach and my gut won't be 'normal' (well my normal anyway ha ha!) for a couple of days.
If i do know that i will be drinking, i might take an immodium before hand and that usually helps somewhat - although this obviously isn't a great idea longterm
As the others say, i guess it's a question of personal choice...