It's hard for me to generalize on which type of speaker (planar vs dynamic) produces better timbre, because there's a ton of variation on that front within both types. Some people believe that planars are "faster" and offer more detail, but I wouldn't generalize and would again argue that there's a ton of variation IME in the perceived "detail" delivered by stats vs planar magnetics vs ribbons, and (to a lesser extent) among different designs within each type of planar.
If you're looking for an advantage that's generic to planars, I'd agree that it's mostly related to the dispersion characteristics. The reverberant field usually sounds richer and more natural to me, possibly because there's less variation in horizontal dispersion vs frequency in most planars vs most dynamic speakers. Imaging also differs qualitatively, as does sound staging. However, personal preference is likely to determine which presentation you prefer on those fronts.
I also feel that dynamic designs have some common advantages (bass impact, for one), so it's back to trade-offs.
Have fun with the search.
If you're looking for an advantage that's generic to planars, I'd agree that it's mostly related to the dispersion characteristics. The reverberant field usually sounds richer and more natural to me, possibly because there's less variation in horizontal dispersion vs frequency in most planars vs most dynamic speakers. Imaging also differs qualitatively, as does sound staging. However, personal preference is likely to determine which presentation you prefer on those fronts.
I also feel that dynamic designs have some common advantages (bass impact, for one), so it's back to trade-offs.
Have fun with the search.