The 128K summer D1 deal I mentioned above is about 2.5 - 3 CPM compared to Z fares from most cities. If you don't understand the nuances of Skymiles program (like advance purchase and RT requirements on many of the better deals -- listed in the fare rules) and simply treat it like other programs, then yes, you will be lucky to find anything better than 1.5CPM.
I'm not sure this is a ringing endorsement, given that earning rates are similar with DL to other programs. I do think the Delta product is good, but they definitely pay people less (in flight awards) to use it.