Hexagon's modeling tools are more complete and elegant to use than Carrara's. The fact that you can export a model in Carrara format means you can get all the benefits of Hexagon's tool set on low poly models but then have the smoothing information become part of the Carrara model - saving some memory and scene weight. 

For my system (OSX 10.5.7), unfortunately, Hexagon is really finicky now and crashes very easily so I've been using some other solutions. Hexagon has some excellent, common sense tools that aren't even part of some more expensive modeling software. I miss using it.

Mark