Its all about disclosure. It is similar to knowing whether your produce has additives or not. Whether it be a section (which I prefer and/or a disclosure statement that is very noticable in the actual forums or both. These measures are all a step in the right direction of truth.
The question raised is, will this open the forum up to more commercial content. Perhaps. But it is clear that commercial content has already been allowed. The precedent has been set and commercial content is growing (confusingly mixed with non commercial content), so disclosure at this point is essential.
I think that a seperate area is the best way in that it keeps a non comercial area intact as one body. Then those who want to do a comercial forums block on their personal settings could do so.
Today we have yet another forum, this one for a herpes product. The precedent has been set. Time to deal with it in a meaningful and proactive manner.
My intent would be to have a commercial area and placee the many forums we have under that style, into that category and place an easily seen disclaimer in the forum as well..the details of the disclaimer to be worked out.