I am not sayin the HD650 is more dynamic, bu rather that this concept is either meaningless or at least not well defined and very dubious.
probably. There is so much talk about "dynamic bass", "planar bass" or BA bass (in IEMs), I suspect it is mostly invented.
Even this is a very flimsy concept. Every headphone that is capable of delivering the highest frequency in the audible range, 20kHz, can swing something 20,000 times per second. How could this ever be slow?
Yes, I stated this several times already. The stock tuning of the HD650 has even less bass than the Clear, but even the Clear is very short of the Harman target, so BOTH require EQ. And with EQ, I strongly doubt that any of your mentioned points (bass, "transients", "engaging", "dynamic sounding") is weaker in the HD650 than in the Clear.