Digital BW, The Print

What's the maximum dmax of the LK ink as measured when printing a QTR calibration chart on glossy papers? I remember with Paul Roark's UT7 inkset it was actually possible to print both glossy and matte prints with the same inkset by simply using the LK ink as the darkest ink in the curve. I wonder if a similar approach would be possible on the 4800 as that printer also has two gray inks. Or would the dmax be too low? 

As I wrote in another thread I'm considering the 4800 printer, and the black ink swap is what's holding me back. So I thought I should check this too before making my decision.