I think in general, having a physical keyboard is a great idea. As for whether or not to go with the ASK or separate BT keyboard, I think the first question to ask yourself is, "how often will I be taking the keyboard with me?"
I have found for myself, with the 1st gen 12.9 Pro, having the ASK made all the difference in productivity. I also have the smartcover. The ASK is the thinnest, lightest, and most integrated option for the iPad Pro. The downside, because of the design of that original ASK, when attempting to use the iPad without the ASK in a mobile setting, I ended up with an unwieldy albatross. Completely unfolding that ASK makes it insanely long. You won't have those problems with the new ASK.
If you plan on primarily using the iPad Pro as a tablet, Pencil for handwritten notes and photos, then it might make sense to have the folio case and separate magic keyboard. This gives you the flexibility having the keyboard only when you need it.
It's a bit sad that there is only a folio case and no smartcover at this point. The benefits of the thinner Pro is offset by the added thickness of the folio.