I'm not quite sure why the BassXX is described as a "filter-based" preamp in their description--I don't see any indication that it's any different from any other typical 3-band set up with sweepable-frequency mid control like the EMG or the East.
The ACG, and other filter-based preamps like Wal and Alembic, are a whole different ball or wax. I've owned both Wal and ACG and played the Alembics, and you really have to approach the EQ very differently.