The article relating to the recent court case is completely misleading.
The entire judgment is here:
http://www.austlii.edu.au/au/cases/vic/VSCA/2011/316.html.
The Court of Appeal said the sentence was too low but declined to interfere for a number of reasons that have more general application, such as double jeopardy in sentencing appeals and that he would have gone to an adult gaol. The Court of Appeal said any suggestion that because the harm of this drug had not been established it was to be treated more leniently was wrong, and one judge at least said the initial sentencing judge didn't even approach it in that way.
However, I believe these sorts of "harm" based approaches are applied for some drugs for which there is almost no market and no notoriety. For drugs that do not have an established market, and have not impacted the community to the same extent as the common "hard drugs", most sentences imposed would likely be less than those imposed for similar quantities of established drugs.
Generally evidence would have to be led about the particular drug for the judge to take its level of harm or the danger of it into account. Judges certainly cannot take judicial notice of the harmful effects of an obscure tryptamine for example. Whereas they can and do for methylamphetamine. They need to rely on the fact that Parliament has made it illegal and if they are available, the threshold quantities of that particular drug for different scales of offending.
For example, sentences for piperazines posing as ecstasy, even though for all intents and purposes the offender should be treated in the same way, I bet would be treated more leniently. We of course would want the offender treated far more harshly, but that will not happen.
The reality is, judges hate drugs that cause them (and the community) problems. All day long they have to sit and listen to the tales emanating from the trails of human wreckage and inevitability these people have heroin or more commonly methylamphetamine addictions (and a host of other problems). And you cannot blame judges for coming down on meth dealers with a tonne of bricks when the vast majority of all property crime and certainly armed robberies that they deal with is committed by those desperate for money for meth (to help soothe their host of other problems).
Other drugs, such as LSD and MDMA, get a bad rap because they are fairly notorious amongst younger people, and judges, rightly or wrongly, believe they are very dangerous. Further, MDMA is unavoidably grouped in the methylamphetamine basket, because it is an "amphetamine". Most judges believe MDMA is addictive yet no one corrects them on this. Unfortunately, some defence lawyers need to become more knowledgeable on these issues and start putting evidence before the court which might address this imbalance.