I've had a chance to use the updated index to the 1940 Census for Ohio on FamilySearch.org, and it appears to me that it is very well done. Using it, I was able to find a couple of families very easily that presented some problems with the 1940 index on Ancestry.com.
For example, my overall search for my boyhood neighbor, Lawrence Betts, led directly to him on FamilySearch. In Ancestry's index, he was indexed as Lawrence Betta, and I had to scroll through a list of results before I spotted him, along with his father, Harold.
Good job, FamilySearch!