Allan,
I actually tried that technique last year and it worked very well.
This may be even more heretical but I discoverd this method earlier this year. I had died some feet gray and they were too dark for my taste ... thought I had ruined them. But the hair near the bottom of the foot was just the color I was looking for. I cut a small clump, cleared out the underhair, and tied in the clump that held the underhair, and trimmed to size, Made a great looking comparadun, and I had a chance to fish them last week and they worked very well.