I really dont like the acronym expansion part of the system. There is little way that any thread or forum is going to get ranked for a phrase unless that phrase is in each of the title, meta description and in the text of the page. A mere expansion of the acronym in the url is not going to help ranking at all. In fact, it would lower the ranking for acronym in the title etc of the page.
I am most definately not selecting this option for my forums, and consider that it is doing the community a disservice by having it available as an option.
Where there are alternatives that are still best practice, fine, but not alternatives that are negatives for SEO.
I similarly do not like the deletion of stop words. But I will save discussion of that to another thread.