If you were seriously drinking a half a case a night (what's that, like twelve beers?) then yes, cannabis is a FAR less damaging euphoriant (in fact, I'd say that cannabis on a daily basis is less damaging than TWO beers a night!). Your liver loves your decision and your lungs aren't too bothered by it :thumbsup:!

EDIT: I just noticed your from the UK. Are you smoking straight bud or are you mixing tobacco in with it? (because it would be better if you didn't)