Mixing Angelus and Fiebings SUEDE dye???

[LMP]

I always hear that mixing Fibings and Angelus dyes has bad results.  I am wondering what that result is?  a color issues, bad chemical reaction, etc.  Same for SUEDE dyes?  I am wondering because I need to darken my only green suede dye (Angelus), and the Fiebings Suede Black just happens to lean green, and very similar to the hue I desire.  It would be just perfect if I could add that instead of the Angelus Black which leans a totally different way.  I tried a swatch and it seemed to work.. wondering if there really is a bad result, and is it something that would show up later?... like causing the dye to do weird things as it cures, etc...  Thank you.  I would love to hear from someone with first-hand experience.  Thank you.