When comparing the performance measurements, the 118HT certainly has a performance advantage, but not a really major one until you get to frequencies above 60 Hz. It has been tested in depth
here at data-bass.com. It looks like it has between a 2 to 3 dB advantage against the VTF15h mk2 at 20 Hz and below, tied with the VTF15h mk2 from 25 to 40 Hz, and has a roughly 4 dB edge against the VTF15h mk2 above 60 Hz. JTR makes some killer products, but with the 118HT you are not getting double the performance of a VTF15h mk2. You need to step up to the Captivator 1400 to double a VTF15h mk2.