More quickly than expected, the initial results for the 12 marker test are in for my Dad's DNA sample.
They can be viewed here:
FamilyTreeDNA have sent us the names of over 750 men who also are matches at this very basic level of testing. None are Fitz(-)Henrys, which just goes to show that the basic level tests give a lot of false postives.
However, there is a gentleman by the name of Mr. Paul John Mac Henry, Sr., and I will be watching this name with interest when the more detailed results come in. This may be an ancient Irish variant of the Fitz-Henry name.