I haven't been on Stax for the last few weeks, but I am glad to see its still loved. Mindstone rubs me the wrong way. I dislike it. The advantage of Grim was that sometimes you got to 3 mana on turn one. That's really the whole point in running it. If I was looking to cut them (And I am) I would not seek a bad alternative, I would look at how I can adapt my new slots.

Personally, I like Walkers. I am looking at a Walker build right now, but I think that will end up closer to Affinity than Stax.