This is an excellent proposal.  It's like Heller.  That monumental SCOTUS case affected an area of America "not exceeding 10 miles square"; yet, it led directly to McDonald which extended the impact to the 50 States!  This legislation is GIGANTIC in that it is indisputably Constitutional!  There is NO Constitution-based argument against it.  DC is Congress's mouse and DC will do as it's told.  Now that the Constitutional argument is out-of-the-way, it's merely a question of whether the proposal is one which will gain the approval of 1/2+1 members of both chambers.  I want to see if my Representative and 2 Senators will vote yes/no on this proposal.  Every American voter - be s/he for or against the R-BA - is entitled to know whether her 3 representatives approves/disapproves of carry in DC.  Every American voter has a right to travel to the seat of government and petition for a redress-of-grievance.  This is outside the scope of States' rights.  Let them vote!