For my own 2-cents, once I learned QuickCheck[1] and Parsec[2], I found myself slowly rewriting them for every language I program in.
> Will it help me professionally?
Speaking as another professional, probably not.
I love Haskell, but my colleagues can't deal with it. They can't write it. They don't know functional programming. And to be entirely honest, they will never understand Monoids, Monads, or macro-hacking.
> ...Help me being a better programmer?
Maybe. If you like already like to think of software axiomatically, then yes, it will make you will make you think of software more conceptually.
But honestly, getting javascript, ruby and go under your belt will also make you think differently about software, and those are more practical languages.
