jayb:
This is potentially a very difficult decision for you and a very difficult recommendation for anyone to make. As far as I'm concerned I've never heard a single thing negative about any of the men mentioned above. I have heard nothing but praise for the quality of their work. I doubt that you would go wrong in choosing any of those mentioned above. I've seen examples of all their work and it's great. I also know there are many others that are capable of doing the same work. I spent a considerable length of time planning a new gun and considered the same things you mention and many others.
I chose Kirby Allen to build my new gun and I can say that I've never regretted the decision once. I find Kirby easy to work with, easy to reason with and find that nothing gets left to chance. Every minute detail gets worked out, everything gets planned fully and you will not be in the dark about anything. Something I would look for is that the smith you choose should be active in the type of shooting you are planning. All of those above are, so that's a positive.
Kirby will work with you in the planning of your new gun whether it's a rebuild, remodel, re-barrel, upgrade or a full blown custom. You will find that it really makes it easier to work with a gunsmith that has done it all many times before.
Your decision may even come down to where you are located in relation to the gunsmith you choose. If you live close to a competent gunsmith that may influence you decision however with shipping as easy as it is, everybody is only a day or two away.
If you're like me the hardest part, after making the gunsmith and component decisions is the waiting. I bug Kirby occasionally but have found that as each step progresses and status changes that I am informed. I can tell you from experience that when you lay down a sizeable chunk of change for a new gun you will really appreciate a man that communicates freely with you, the customer.
Put all of your ideas in an e-mail and hook up with Kirby. Won't cost you anything to ask some questions and I'm sure you will be happy with the process. Good luck.
