The X3R technology is much more accurate in pinpointing resonance peaks, so the overall response is smoother. The newly integrated acoustic vortex also adds some "general smoothing" to the area between 6-10 kHz.
I'm strongly against the concept of target curves because I believe that every acoustic concept deserves a specific tuning. The occlusion effect (how closed off our ears are) has a big impact on how we perceive bass: An open headphone with flat bass may sound more impact-full than a BA earphone with a bass shelf. So alone the amount of occlusion (highest for BA earphones, lowest for HD 800 S) requires different considerations for tuning. Target curves are too simplistic to cover this complex behavior.
Apart from that, I talked with crinnacle, and I believe his in-ear target to be more tonally neutral than the Harman target.
