The release candidates have been in Debian/sid for a week or two now. I have not noticed any problems. It looks like the only differences between rc3 and the stable release are some documentation changes. If you are feeling adventurous 2.0 is in experimental:

    root@ronin:~# apt-show-versions  -a git
    git:amd64 1:1.9.0~rc3-1 install ok installed
    git:amd64 1:1.9.0~rc3-1         unstable      ftp.us.debian.org
    git:amd64 1:2.0~next.20140207-1 experimental ftp.us.debian.org
    git:amd64/unstable 1:1.9.0~rc3-1 uptodate