My experience with all types of Dipole's and Bipolar's in general, is that diffusion generally works best behind the speakers! The speakers were mostly designed for you to hear "the back wave" of the speaker's sound propegation, and absorbing usually yields a more "life-less" sound!...effectively the opposite of what the bi-pole/di-pole is trying to give you!
Each room may varry a bit, depending on other acoustical factors. But I've tinkered extensively with acoustics with bi-pole/di-pole speakers and acoustics together, and I just tend go the "diffusion" route!
One thing that could help here, is to have dipole's set up out in the room a bit more!(still should yield good frequency response however, as a priority). If you can do this, the time in which you hear the "back wave" from the rear wave of the speaker should be delayed quite a bit in proportion to the first wave that hits your ear from the front drivers of the speakers, proportionately!...limiting immage blurring(designs will varry). This will cause less immage smearing where little or no acoustic treatment is used. But you have to, like with anything, experiment.