The DoD:S beta has been live for almost a month. Currently over 100 servers are running it. You need to change your STEAM settings/preferences to "allow beta participation". Then, if you already own DoD:S, it will give you the option of downloading the Beta for free.
Give it a run...I like it much better. Although it LOOKS similar, the cone of fire, and hit registration, seem to be quite improved. It also adds some TF2 style features, like DOMINATION/NEMESIS, and achievemenets.