It's been an interesting 3 weeks of research and I've learned enough to at least know what I don't know! I know there were many ways to skin this problem and many of them probably would have worked. I went with the company that gave the impresison of knowing the most about the duct system and had the ability to actually measure flow, pressures, velocities, leakage, both home leakage as well as duct leakage. I did give some thought to using a 3rd party to provide this service if I had gone with the zoned system which was proposed to verify thier work, though their quote did not address the home leakage at all ( i.e., the tents ). Course I don't want my house to be too tight as that can create other problems ( NC is notorious for Radon and while that in a nutshell is my work and I'm not as concerned as many are with it, I am aware that a really tight home can create issues with it ).
In the end, I felt I made a decision that will lead me to a well designed, well installed and well tested duct system along with some nice equipment, probably nicer than I truly needed truth be known. I did get a bit anal about the duct work but some of that also went back to choosing someone I trusted. The guys I worked with on this system are also the guys doing the installation. No salesperson to deal with.
I do think the other installer could have done a good job and no doubt from our discussions did things in many ways as described here. Biggest problem I had with their quote was (a) the salesperson.. I was ok with the owner but the salesperson irritated me as he was more interested in discussing their awards than he was in discussing the system, (b) although I was promised by the owner that they would perform detailed heat load calcs after the contract was awarded, their initial bid resulted in 2 returns that were undersized and at least 3 supplies that were undersized. These cals were done by the salesperson and the owner did apologize and assured me it would be done right at no cost to me should the calcs result in needing larger of anything. In the end I did feel they could do a good job but I simply had more faith in the more detailed duct installers.
I have a couple weeks before we get close to the job date so I'll try to get some photos taken of my existing duct system. It's really a bad layout and horrible setup. I had 3 installers who said it "looked fine to them" and they wanted to keep it intact, while another wanted to chang eonly the ductboard trunk but keep the felx duct supplies and boots.
INterestingly, if everyone had quoted a new duct system + new components, all of the bids would have been within 10-20% of one another. The one I chose was NOT the most expensive but was getting there. I did, though, have a lot of toruble finding installers that made me feel comfortable and when spending this kind of money I simply wanted to feel like I was getting a quality installation without taking unecessary shortcuts. Guess time will tell