I don't have any experience with the Def Tech BP7001s, but do have some experience with dipolar and bipolar speakers that might be applicable.
Briefly, the ear does not like early reflections but it does like late-arriving reflections. The ballpark transition zone is around 10 milliseconds. Sound travels a little over one foot per millisecond.
Cjmbl, you might try placing your Def Techs 5 or 6 feet out in front of the wall behind them, such that the reverberant energy from the rear-firing drivers begins to arrive after about 10 milliseconds of time delay (round trip distance of 10-12 feet). Even if room aesthetics prevent your leaving the speakers in this location, try it as an experiment to see if the problems you hear arise from the early onset of a lot of reverberant energy, or from something else.
A good dipole or bipole can sound rich and lifelike when set up appropriately, but with a significantly sub-optimal setup they will not sound as good as an equivalent monopole.
Duke
dealer/manufacturer