I have talked to my friend Dave Norin as an independent gunmaker who uses both actions and he likes both a lot. Also, having met Karl Webber and Greg Hein, I do think they are very fine people. If you're going to have an independent gunsmith build your rifle, why don't you ask him for his opinion? Or, if you're going to have GMA or Hein build you the entire rifle, then you could have a word with some of their clients. I am sure both have several highly satisfied clients including members over here.

Good luck and do post when you come to a decision. Don;t forget to post pictures of your rifle as she is being built.