Now I tried having a discussion with some wrx guys about this.
My intial impression is that most of them were just gobbling up what people were saying on i-club and not listening to any other points of view.
I for one like tuning with an safc. Sure it's a rudimentary method and does not have the flexibility of some other methods but it's also cheap.
You definitely need some kind of datalogger or at the very least an egt gauge.
I'm no wrx expert though, so don't take my word for it. Maybe some of the wrx tuners can shed some light on a key aspect of why an safc does not cut it.
Note: I remember one guy on one of the wrx sites tuning with an safc and getting good results.