[lengarvey]

One of the biggest reasons to switch is that Slim supports streaming and Haml doesn't, or at least won't until the next major version.

Sources: https://github.com/stonean/slim#slim, https://github.com/haml/haml/issues/436

[aoe]

Are there any other pros/cons in switching to Slim? Other than the syntax of course.

[OffTheRails]

I'd say speed and syntax are the main reasons. I've used both Haml and Slim over 5 or so projects and the jump doesn't feel all that significant. If you know Haml, you can pickup Slim within a couple of days at most.