Well, I once was the Rational France resident expert on Automated Software Testing issues and one of the software quality dudes. Great company (before IBM bought it, dunno now, heard some good things).
About Rational Rose and hand modeling :
same difference between a paper notepad and word. You can use both but don't change your mind or try to make anything evolve with hand modeling... I tried Visio (microsoft omni purpose modeling software) and it's a bit too limited. I tried other products (that actually supported the whole UML set and not a mix of Booch OMT and UML) but it was not as well integrated with other software development lifecycle tools...
Now Rose XP is out and I heard it's a great tool (almost perfect actually from my current customer). But it doesn't replace the brains behind the mouse 🙂