I think the remap has a lot more potential than the safc, by the looks of things pointed out by toshi.
Safc, will just basically tune your air fuel ratio's and thats it. Well you adjust the fuel curve, but i think the remap can squeeze a lot more power.
Safc will probably also cost a bit more than the remap.
Hopefully someone else can explain the difference better than me..
Well im gonna give this remap a go next week probably.