> I'm not 100% sold.

The vast majority of people that use it aren't, but that's a feature :)

Manifold isn't an all-or-nothing proposition. It's architecture is modularized so that you can select the parts you want à la carte as separate dependencies in your build.

> At the very least, I prefer not to have any surprises in my codebase

But manifold surprises are pleasant ones :) As with any library or framework, it's a design decision: does it provide enough productivity and opportunities to offset its presence in your project? It's not a panacea.