Use Extensions or Extend Controllers? Or What?

[mdvaldosta]

There is some functionality I'd like to override; for example, the redirect location after logging out. The methods in Backend.php are easy enough to modify, but I'd prefer to stay out of the core. I read that extensions and extending controllers are planned features; until then, do I have to hack the core to do this?

What about adding new controllers to the Bolt folder? Anything to be wary of?