This is just another reason I would like to see the NEC on a 5 year, or maybe even 10 year cycle. The TAC could deal with truly bad stuff that slips through but it would be less likely to happen if the cycle was long enough to really analyze changes for a while before you print them and let the current code settle a bit before you change it again. If we were just putting the finishing touches on the 1999 code changes for a 2009 release we would actually have AFCIs that work before we jammed them down people's throats and we would have had time to discuss things like this MWBC thing.
Nobody ever said you couldn't install any listed item like a TR receptacle or an AFCI as soon as it was listed. Leave it up to the manufacturers to sell them to the public. If the public really is convinced this is a good idea we will be happy to put them in.
Could you sell them? Sure, this is the public that buys "green plugs", electronic varmint repellers and "baby on board" signs.
