I like the separate Buy/Sell for several reasons. Organization is one, keeps things all together under one easy to find section topic.
If a person is looking for a truck, parts or whatever they don't have to go nuts clicking back through post after post and into archived posts to try to find it.
Example: A post in a single-section forum titled, '69 Sweptline Crew Cab' could be a question about the master cylinder, or somebody saw one parked in Toledo, or it was just stolen, who knows 'til you click on it & read? Saves a lot of wasted time & energy to look in the For Sale forum section.
So far the vast majority of users like the new format, the many additional features and the ease of use. It has a whole new look & feel, more user friendly, many more options and a very good software package. I also notice a lot of new names so membership has gone up, along with participation, and more posting action. Seems to be a booming SUCCESS!