Do link units effect the order ads are served in the html? It's well documented by Google that the order of adsense in the HTML makes a difference eg. if your middle of your content placed advert gets better CTR than the top of the page banner then it's worth making sure the best CTR ad is first served in HTML to receive the top payers one question this leads me to is does the link unit ads effect the above too?
I asked just the same question in the Google help forums today too. I don't think that the link units are taken into account with the order because they are not displaying Ads on your site directly. And I also think that the display order of Link Units among each other has no effect either and they are treated as separate identities. However I like to see an official Google employee response to that.