I use link units and they do convert. Most people don't use them and only use the image/text ads. Why not put at least 1 link unit on your site and see if they work out well on your site. Make sure you use ad channels on your link units, image/text ads.
On the adsense blog there is a blog post about adsense link units that's a good read.
If you’re as excited about link units as I am, then you’ll be happy to know that they’re now better than ever! Link units are a different type of ad format which display a list of topics relevant to the content of your page. When a user clicks on a topic, we’ll show a page of related ads and you’ll earn from valid clicks on those ads. Many publishers have found that link units offer monetization similar to that of ad units and provide a more integrated user experience.
In our biggest performance overhaul to date, the link units engineering team recently...
Continued at: Link units revamped
Comments about the news from google and if you have been using the link units for awhile, have they did any good for you or a waste of space?