I've seen dipolar open baffle line arrays on the web but most of these designs have been directed at arrays of low cost drivers. These designs clearly don't have all of the necessary compensations as Dr. Linkwitz features in his Orion and Phoenix designs. I would characterize the open back line arrays with the cheap drivers as interesting but likely flawed because of their uncorrected imperfections.

Hence, you likely would not be interested in a low dollar line array of cheap speakers paired with a state of the art DSP compensator.
To match up with the DEQX you would need to have near world class drivers like the Seas Excel products or equivalent and true ribbon tweeters (Fountek, Aurum Cantus, etc.) in my opinion.

None of the commercial line arrays that you mention are open baffle. The Monster Cable speakers are certainly not derived from world class components. The Dali line array and some of the others you mention look interesting but their costs are well above reasonable levels for most folks.

My buddy Rick Craig (www.selahaudio.com) has some interesting line arrays on his web site and I can vouch for their design soundness and excellent component selection. He doesn't have an open baffle model but he does custom designs if you are interested.

Jim