Terry,
Although it is indeed exaggerating to compare them to the Louvins, the X
comparisons make sense to me. I think these come out more when you
see them live. They have certain sounds, harmonies, etc. that have a very
"X-like" effect in that context. I forget which song it is, but they
sometimes cover an X number live and it sounds damn good in their version,
very true to the spirit of the original, etc.
Overall, however, I find their writing and sound pretty unique. They are
truly not a cookie-cutter outfit and have that rare thing, a sound and
style truly their own.