I believe you have sussed it out just perfectly. The dmoz listing is the best of the bunch. This is why it pays and pays again to look hard at a Yahoo listing. While the yahoo listing can provide some raw traffic if you hit your kw's, the dmoz listing will have more affect on Google than the Yahoo listing. While the ODP listing also has the potential to spawn viral children in the form of recip links, other search engines that use the data, and other sites that use the date, the Yahoo listing will pretty much lay there and produce only from Yahoo.