Not sure what the pros are against Brunch. The author states:

Brunch also tries to do partial rebuilding rather than caching; see section “Caching, Not Partial Rebuilding”

But the end of that section seems to imply that it's still something that needs to be implemented per-plugin:

Plugins that map files n:1, like Sass, need to be more careful about invalidating their caches, so they need to provide custom caching logic.

I'm excited to see what comes of it, but still prefer the idea of simply running `npm install (sass|jade|less|stylus|coffee-script)-brunch --save`