Yes, the (current version) B3K, B7K, and B7K Ultra all use the same basic distortion circuit and general pre-distortion EQ curve but with some different features that could change the basic tone options- the EQ on the B7K is post-Blend control and so affects both distorted and clean signals while the pre-distortion curve you mention only affects the distorted signal. The current iteration of the B3K replaces the "Attack" switch with a mid-boost switch and there is a general Tone control (variable LPF) not found on the B7K. I haven't tried the current B3K, but the "Attack" on the original B3K and the current B7K is a pre-distortion treble boost (or cut as the B7K offers as well) and makes a big difference to the tone and distortion character when engaged- not sure if the mid-boost is also pre-distortion boost like the Attack and Grunt boosts. Without the Attack engaged and with the Tone on the B3K turned up all the way I would guess the B3K and B7K would sound roughly the same. That said, in reality there is always some audible difference between every example that DG in the past has attributed to "parts tolerances". I've had an earlier version of the B3K (when it still had the Attack switch and lacked the Tone knob) and it sounded mostly the same as the B7K I also owned at the same time when I left the B7K EQ flat.
