Tom,
Of course that should be the question, but are most owners saavy enough to know what the best possible course is? They do understand the lowest price.
Typical questions include specs for bunker, green mix and tee sand, whether to use bunker liners, etc. No matter who is in charge, these questions must get answered. If its a gca before a bid process, the discussion can center on the cost-benefit ratio. If its a discussion had after the bid or negotiated price is fixed, it likely centers on cost. It doesn't really matter what the contract scenario is, its whether the budget is fixed.
Killian and Nugent used to do the Owner as contractor method, with young guys like me in charge of the project. The best I ever did over a contractors price was a 15% savings. I saw some projects go 15% over. KN charged for project management (as do any DB contractors) and used a mix of sub contractors of varying ability. Of course, sometimes you hire the best golf contractor in the world and get a lot of subs, too.
In general, someone has to manage the project and pick the subs. While the owner or gca might be able to do it cheaper, especially if they know the right people, the contractor brings experienced people to the table in most cases. Saving their profit and OH might be offset somewhat by their people also doing the work faster.
There is also some benefit in having the three part system where the gca argues quality, the independent PM argues cost and the Owner decides. The Contractor can certainly chime in, too.
I am doing a DB with LUI right now. In the field yesterday, we through out the grading plans I had initially prepared. Their input was that they needed something to build fast with dozers until the scrapers got down there. I was fine with that as necessity is the mother of invention. I reconfigured some tees, etc. to make work for them and I was the final judge of whether those design changes worked, and I think they will actually work better than what I had concieved on paper.
In other cases, I have been involved with design build and the contractor who stood to benefit from reduced work decided that my 10 foot high earthforms really looked better at 2 feet high. In many cases, holes get altered because they send the scraper back at the end of the month to save rental fees and the option is to build the best hole you can, as long as you build with dozer cuts. Its not hard to see design problems with that either.
Again, its the people. If you want a great design in design build, the people in charge have to be committed to that. Which, I presume is the reason you and Pete Dye fashion your businesses as you do.