I have used Dirac and currently use Anthem's ARC/Genesis.
For each, I only did/do correction below about 400hz or so, and in my room they made noticeable improvements. Doing the room correction above that range it started to sound artificial to me.
That said, room correction, IMO, is a must have...with and without room treatments. I am very happy to see Dirac starting to be offered in equipment at lower price points.
BTW...for Dirac, it is important to note that the full version gets you much more "tuneability", but that usually isn't included when you buy the pre/pro.