Which VR-4's did you hear? Both the new and old VR-4 have super bass response, however the new VR-4 Gen 3's bass response can simply be described as "Lighting Fast Attack", they are really fast.
I believe Albert Von Schweikert used to work for Harmonic Tech for a time. Maybe the Harmonic Tech cables are especially beneficial to the VR-4's?
Which Sonic Frontiers amp are you driving your NHT's with? Which NHT's do you have? Previously I owned the 3.3's and VT-3, the 3.3 killed the VT-3 musically. However the the VT-3 shear weight in the lowend was something that you have to hear to believe. They absolutely rocked with no apologies.
In the End though I came back to the VOn Schweikert's, something about the excellent low end response, coupled with the clean midrange and upper end. I love them.
Do to my limited budget, these speakers will be the last I purchase for few years. I need auxillary components to keep up them.