The primary advantage of kallitype over VDB is that it offers the potential for extensive contrast control, just as you have with Pt./Pd. By contrast, VDB has little or no contrast control. This is a very important consideration if you are working with in-camera negatives because if the negative is not developed to the exact contrast needed for VDB you will never be able to make an optimum print. If you plan to print with digital negatives, however, you could tailor the negative very easily to fit the process.
Both VDB and kallitype can be toned with gold, palladium or platinum. In toning the more noble metal replaces a high percentage of the silver, giving the print permanence on the order of regular Pt./Pd. prints.
VDB prints toned with either palladium or platinum are much warmer (browner) than kallitype prints, which tend to be a warm black.
Originally Posted by Mark Fisher