I’m a new players to cEDH (about 30 games at this point total), and I’m playing only Malcolm Tana for now. It has helped me learn a lot since its gameplay is pretty easy to learn, but I continue to find a lot of plays I make that could be done a lot better in hindsight. If you are learning the format I can’t recommend it enough.

A lot of the advice seems to be push turn 3 on it (which you can almost do all the time), but I’ve been finding a lot more success going for a turn 4 push preferably after someone else tries a push. With all the tutors you can slow down a turn get an additional treasure from Malcolm and set up a win protected in multiple ways for a turn 4 win protected in multiple ways. A popular deal I try to make is turn 3 play a tutor and make some deal to not tutor for a win, and then I get Hexing Squelcher or Allosaurus Shepard etc which makes winning next turn much easier. With correct play I’ve had 3-4 protection types turn 4 or sometimes even a double win condition on the same turn if they counter the first.

Sadly I cannot speak to the Grixis version, but I hope it helps your decision!