I always use multiwire branch circuits in residences, but we are all EMT, so it just makes sense to do it to keep your wire fill down.
It helps keep things straight in the panel if you have a color scheme and pipe things in a sensible manner.
Redsy, who are these "many" that think the whole house will be AFCI? Maybe I'm just out of the loop, but that sounds excessive to me. What next, sprinkle and monitored alarm panel? why not just outlaw wood? That way you reduce fires of all causes.
