I have been messing with clays in one form or another for automotive use since 1985.
The Mequiar's is not made by them, the reason it appears to fall apart is the lub that is used.
They don't even make their clay, it is bought from the old Zebra Clay people.(as are a few others mentioned here)
Then you got U.S. Chemical, Ashland Chemical (sells it in any color, grade, size the marketing company wants), All-Brite, etc.
Then the Japanese companys, and the patents.
What ever makes one happy, but this fellow might as well use it, it won't hurt his paint anymore than anyother clay. Just will smear a bit sometimes, not always.
Sorry I stuck my nose in.
:down