Of course I respect yuor opinion and experience. First, let me say I have a non-modded HE6 (I don't have the "dexterity" to do such things) since 4 years now, and I still do love the sound of these hps. I have driven them with anything from 1W to 30W, currently using a Taurus MKII (more or less 5W at the HE6 load) and a Spectral+Pass (200W@8ohm, 25W at the HE6 load). My experience with the HEK, owned since 1.5 year now and driven by a 300B SE amplifier, is that it has slightly slower and less precise bass than HE6, but way deeper. My experience with the Utopia, admittedly very short, driven by the same 300B ampli as the HEK, is that it has slighlty less deep bass than HEK, but more precise, fast and controlled/undistorted than both HEK and HE6.
Maybe with a modded HE6 driven by a different amplifier, I would listen to the same as you described.