If the international regulatory body makes rules on transportation, health, security, borders, etc instead of our elected congress (which is the case since the SPP is solely an executive branch project with no congressional oversight), then the American voter will lose our ability to control the destiny.
We Conservatives are for smaller, more responsive and accountable government, not international entanglements and superstate bureaucracies, arent we?
I'm going to go with the "wait and see" crowd.
The SPP is a "concern", but as of yet it hasn't proven itself to be a "danger". And it may actually be beneficial. Only way to find out is to see what they come up with.