I'm not going to go through the trouble (?) of finding a source which verifies the effect of smoking mescaline. Though I know (from everyting I've read) that natives smoke it traditionally (as well as eat, and inhale thorugh vaporization in a sweat lodge). And I've smoked it and experienced quite a powerful effect, on numerous occsions, without the use of other psychoactives.
And no, you do not need to smoke 30 g. just to get a psychedelic experience. I can see the reasoning, but bear in mind when you smoke something it processes through your system dramatically faster than when you eat it. Try eating one hit worth of cannabis and see how noticable the psychoactivity is compared to smoking one hit.
For most substances, smoking is the second fastest means of ingestion, after injection.