Rand,
Are you telling me that the guys you mention are doing their own irrigation plans? They may have a CID on the payroll or under contract, but I doubt they are doing their own. In fact, I tried to get a project off the ground with one of those you name (it never flew, at least not yet), and although irrigation design was included, it was farmed out. Landscape plans should, IMHO, be done by locals with local knowledge of native species and their use. I kind of doubt an architect based in Michigan will have the knowledge to do a landscape plan in FL, AZ, CA, HI, Europe, Asia, .....What is important is coordinating the project and hiring good professionals to handle their specialties. I would be very wary of someone calling themselves a Golf Course Architect who claimed to be an expert in all the areas you mention, worldwide.