Y-DNA to the Rescue?

Two of my DNA contacts came up with some interesting ideas.  First, Brad McGuire mentioned
that the three of us with Maguire DNA but the McCown/McKown surname, were also the same
value, 16, on marker DYS 464b.  Then Pat Meguire, adm. of the McGuire Surname Group
suggested that since about 25% of his group were also 464b=16, that perhaps this indicated
a particular Maguire family line that we could trace back in time.  Then, Brad McGuire
suggests that the following markers and values in combination could identify those with
a McGuire surname that should be tested for SNP P66+.  That would then tie that particular
line of Maguires to which the McCown/McKown lines are descended.  Sounds good to me,
now all that is left to be done is to find Maguires with those specific marker/values and get
them to test for SNP P66+.  The markers and values are as follows: DYS 390=25, DYS 481
=24, DYS 640=12 and DYS 464b=16.

Brad McGuire is the adm. of the Airgialla Mag Uidhir Group and also points out that some
markers mutate faster than others  and that some SNP's mutate within a given family.  For
example, all five of the markers that separate me from being an exact match for the Maguire
modal at 25 markers are fast mutating and he mentioned that fast mutating markers could
take 3,000 to 4,000 years to mutate.  To me, that would put past mutations well before the use
of surnames became common in Ireland, about 1,000 AD.  I don't know yet whether
mutations repeat over the years and began at different times or if they vary within a single
family line.  I hope to have more on this later because I surely am at my limit tonight.