In defense of SPDs (I call them "small planar drivers" - they can be circular, like in Moondrop May, or BA-like, as in 1More Penta) - they can give good results, especially if used for a narrow spectral range, as in Phoenixcall, Penta and May.
May really impressed me with the smoothness, even cohereness, of the driver integration, where SPDs seem to triumph over BAs.
On another note, my Symphony is on the way, the graph looks like "a cursive V" - even more interesting to try.
I am really happy that KZ is doing something different than recent Rhapsody and Trio, otherwise they could stuck with non-offensive but not eventful tunings similar to Crin and his followers.
It may be hard for Symphony to compete with May, especially being a bit more expensive and without a luxury box
We will see - that is the most fun of this hobby to me - enjoying different flavours of the tunings, capabilities and limitations of different drivers rather than trying to chase any elusive perfect unicorns