Dumb question time: did they do any testing of this odd plan?
Aside from the backup at ditmars, if they don't have the timing just right there will be yet another back up manhattan bound at 39th where the tracks merge down to 2 through Queens plaza. (where are those switches controled from now? the tower there has become an oversize pigeon nest).
It's a nice idea if it actually works (and far better than that BS years back when they turned the B at QP during non rush hours) but I doubt it will 60% of the time.
Look like I might become a V rider afterall...