I don't like the fit of the Safire for me (top tube felt too compressed) but love my Epic. Here is what I love about it: customizability to the Nth degree. The brain is a bit overwhelming but it is a really awesome addition once you figure it out. When I first got my Epic it felt like a trail bike (super squishy) and I was shocked since it has 4" of travel instead of 5". Then I dialed in my Brain shock to give me a good happy medium. You can almost go completely to making it feel like a hardtail. I did notice the Safire is carbon, not sure if frame composition matters.
Not familiar with the Giant but I did notice that is their race bike. So you're really comparing two very different engineering goals. The Specialized is a trail bike which should have more travel (I think it is 5" vs 4" on the Giant) and a plusher ride but will feel slower. I am on my first race geometry bike and I feel like the bike wants to go! So that would explain your reaction. My husband's friend just got an Anthem this spring and has nothing but great things to say about it.
I wouldn't hang my decision on components like drvietrain over fit and forks, the drivetrain on mountain bikes tend to have short life and you can always upgrade the deraileaur.
Amanda
2011 Specialized Epic Comp 29er | Specialized Phenom | "Marie Laveau"
2007 Cannondale Synapse Carbon Road | Selle Italia Lady Gel Flow | "Miranda"
You don't have to be great to get started, but you do have to get started to be great. -Lee J. Colan