I bought two Vie-Long's from G&C recently as well. One is pure horsehair, the other a boar/horse mix. Both with a very long loft, but narrowish knot. Very impressed with the service, and the prices are competitive as well.
Dr Rick, I read that horse used to be very common as a choice of brush, until about a hundred years ago, during (I believe) the first world war, when horsehair brushes were partly blamed for the proliferation of a very nasty outbreak of anthrax. After this, they fell out of popularity, and never really recovered.
Nonetheless, horsehair whips well, has good backbone, and is perfectly gentle on the face, unlike some would have you think. I bought mine because I thought they would be useful for whipping in my EJ mug, which is quite deep and my thicker-handled, shorter-lofted brushes clang against the inside edges. The results thus far have been great.
The only compaint I'd have about the V-L's is that the finish on the handles is pretty mediocre. One of the two looked pretty beat up straight out of the wrapping, in fact. I might ask Juan for a refund or exchange...