Technically, the Avanti 2 and Avanti Boost are different shoes. I’ve worn both.
The new Avanti Boost FEELS like a 3K spike to me. It’s aggressive enough to roll a mile in, soft enough to run a 5K for (which is what I used it for), but the 3K just feels like it would be such a sweet spot for it.
I’ve seen guys run the 800m in it, but I’d probably give the nod to the Adidas Ambition, or the MD, if that’s your primary event and looking to stick with Adidas.