We should remember that Ack's speakers are Martin Logan Odysseus, hybrid electrostatics that he has extensively and carefully modified to suit his room and system. Although as far as I remember - I never owned the Odysseus , in my Martin Logan phase I jumped from SL3 to Odysseus big cousin, the Prodigy, the panel is crossed rather high, around 250 Hz - it includes some capacitors of tens of microfarad in series with the step up transformer. I think the dynamics concerns presented by most people are about full range electrostatics.
For example the Mark Levinson HQD system, that used double Quad ESL57 crossed around 100 and 6000 Hz had great dynamics.
And sorry, no miracles are possible. No way an Odysseus panel can have the dynamic range and body of a large SoundLab in a medium/large room. But they can surely sound great, much better than people expect.
Again, IMHO single instruments are not a good indicator of dynamic range. I have seen systems that have great dynamic capabilities with drums and brass, and are not able to keep the dynamics of a full orchestra. As usual YMMV.