The problem with capable adjustable HPF onboard amps is in the selling. The average bassist isn't well informed so when asking what the HPF knob does the sales guy says 'it cuts off low end' and the next words out of the shopper are 'show me something else'.
Iirc the Thumpinator is -3dB at 30hz and a 12dB / octave slope, higher than fixed filters on amps but too low for what most HPF users are after. Ymmv.