> Running a large model locally comes down to one thing: how much RAM it actually needs in memory.
Not completely true. It's memory AND memory bandwidth. You can have 1tb of memory but if you have awful memory-bandwidth you'll also have slow tok/s. A3B helps with this, but so does MTP.
From my experience, you'd be better off running the dense 27b-mlx with MTP than the 3.6 version with A3B. You say your model is ~20GB of ram, but the 3.8:27b-mlx is 18GB and gets me very reasonable tok/s, and greater speed if you disable thinking when not required.