The mid bass and upper bass from the DD wont be tight like planar bass, they have control and speed like BA so i prefer mid and upper bass handled by planar, the DD just push the air on 40hz below together with planar bass sound (this is what i wish perfection from my Z1R, little bit perfection tightness on mid and upper bass like my modded timeless, well the Z1R already close to perfection, just me being nitpicking b4st4rd)
A good DD (imo) can still be tight and quick in the bass. The Penon Vortex (DLC driver) is a very good example. It's texturing is retained all the way down to the deepest notes on instruments.