f each state is given full autonomy in how to solve its internal problems (taxes, social policies etc.), the US will have data from 50 different experiments (or even more if internal autonomy is given on lower levels).

I dont thinkl your distinction between the Experimental and the Natural answers. It isnt in the interests of most people to be involved i a deliberate experiment that results in bankrupty, or tyranny...but then it wouldn't be in their interests to be involved in any natural drift that results in the same ends. People who don't want to end up in the New Confedaracy, or the Socialist Republic of the Pacific, wouldnt vote for increased independence.