I have mixed various Black and Tough v5 resins at pretty arbitrary concentrations and use the Tough v5 print setting with excellent results. This was mostly just because I had a tank full of Tough v5 and an empty cartridge, and a Black cart with not enough to fill a tank on the Form 3. So I was just splashing in black until it decided the tank was full to make it print (which is always annoying when you can just look at the tank and see that there is not going to be a problem printing a 25mL object, but there is no manual override to just start).
As the ratio shifts to be black heavy, the cured material behavior understandably becomes more like the rigid black and less like the Tough but I never got to the point where it was brittle before I ran out of my materials.
I would like to get High Temp to print in a medium brown so I’d be interested in results from anyone using a tinting kit on it.