There was an article recently, at Lew Rockwell, I think, discussing Antonin Scalia's thoughts on a "Con Con." He was opposed for much the same reason so many others in the Liberty Movement are opposed. There is no controlling where a con-con could go.
Further, what makes anyone think a government that disobeys the Constitution now will have any greater fidelity to a new and/or amended version? As sincere as promoters of a con-con seem to be, the notion is sadly misguided.
The great need of our time is to demand that our government obey the Constitution we have, and that will take a lot more backbone from the American people. Then and only then might it be safe to consider updating and tweaking to the Constitution.
With Liberty,
Dean F.