Oddly, while I have argued for the flagging (And intend on using it on the sites that I moderate), I am not 100% convinced that it is needed on a site such as SFF. (Yes, this is a change from my earlier stance.)
There are enough very active, high rep users here that the flagging and deletion of spam is taken care of in extremely short order. Increasing the chance of false positives, I'm just not sure is worth the risk.
Now, on sites with lesser traffic (and higher relative spam incidence), such as fitness and health, I believe it is of much higher value. So while I still support the initiative, I am not 100% sure it is needed on the really high traffic sites with a broad high rep user base.