Rafal - a couple of things to keep in mind:

1. As you decrease (or eliminate) the concentration of bromide and replace it with BZT for cooler tones, it is likely you will see less stability in image tone through successive prints. As bromide gradually builds up the tone will tend to become warmer as you go. So consistency from print to print could be a potential issue. The relatively high initial concentration of bromide in Ansco 130 may explain why it is said to be so consistent throughout its working life.

2. Watch out for a split-cooling effect with some warm tone papers. If the base is tinted warm (I believe MGWT is like this, although Ian G. would likely know for sure), you may still end up with relatively warm highlights and upper midtones where there is less silver, relative to the shadows where the developed image has been cooled by the cool/blue-toned developer.

Just some thoughts.