Bipolars typically don't have the "baffle step" which can reduce the lower midrange and upper bass energy, so they often sound "fuller" than a comparable monopole speaker.

Since both the front and rear woofer are pressurizing the room at the same time, the one doesn't cancel out the other except for a wrap-around dip that can occur at the frequency where the rear-firing woofer's output arrives at the listening position one-half wavelength later than the front woofer's output. This can be minimized by several different approaches (I use cabinet geometry - hence my relatively wide, shallow enclosure), and in any event those frequencies are too low to be an issue in sound image localizaton.

Your observations about imaging are correct in my experience. All else being equal there is a tradeoff relationship between precise imaging and envloping ambience, and it has to do with the relative energy density in the reverberant field. In general, reverberant energy degrades clarity and imaging, but can add richness and lifelike texture.

Diff'rent strokes, you know.

Duke