Honestly I don't think it makes a big difference one way or the other. I came from another forum that not only had separate Opiate/Opioid forums, but separate sub-forums for almost every major opioid. There was an Oxycodone subforum, a Heroin subforum, Bupe subforum, etc. This may sound great and well organized but it made it almost impossible for new members to post in the right place when they had questions involving poly-substance use, and a LOT of people did.
I don't know what the problem is as long as everyone is basically able to find what they're looking for and everyone knows where to post and in terms of the latter, it's much simpler here I think. Personally I also agree that separating the threads based on complexity is really smart but this is obviously more subjective.
Really the only other thing I can say is that if any other format were to be considered, I certainly hope it wouldn't be based on the entirely not-objective "draining" nature of opioids and rather what makes practical sense for the forum and its community... just saying. Although even as a new member and older lurker, I have seen this question come up time and time again. Time and time again the answer is, "this is how we do it here, it has worked for many years, and that's how it's going to stay." I dunno, I guess I'm just fine with that.
If it ain't broke don't fix it, y'know?
