I got SCS3 when GOD first came out. I have never regretted it. I still have plenty of agro, and can hold it when I want it. SCS just gives me the freedom to slow a little sooner and be a little more aggressive with my damage (or not have to worry about pulling agro on multiple crit ticks of sisslak). I did make the cleric I group with regularly get it before me though. When the MT goes down, I am almost always the second person to die!
I suppose the usefulness will scale based on your level of gear and the level of gear of your tank has in your normal situation (raid or group) and how trivial the content is that you are doing. I pull agro off my normal tanks all the time and tend to fight against things that will demolish me, so I will take any hate reduction I can get.
I find it amusing that people take not having SCS as a point of pride. Do you also take all of your gear off when you get your unecessary agro? Because all that avoidance gear and stuff is for wusses...real shamans tank mobs in teh face, naked.
