When it comes to engagement of PMC/SMEs for decision support or level 3 - 4 projects, the range of solutions and technologies is quite wide and deep. So, what constitutes the need for a PMC? Where is the value? What are the "must haves"?
The topic came up in a recent discussion/presentation with a major client. That is, what qualifies a company to be a PMC and who are the companies that can offer such service? Here are some thoughts.
First, why a PMC? The answer is simple. A qualified PMC should be in position to engage the required subject matter experts when and where they are needed. This eases the burden on the client to spend time looking for the right people at any given time. 
Next, the value that a PMC brings. This should be in both tangible and intangible terms. As for example, reduced cost of the project and timely delivery. It is well know that DSS projects are risky and many have experienced delays, budget overruns and unfulfilled scope and expectations. A qualified PMC should be able to identify risk areas and initiate actions to prevent these situations.
The adjacent figure is a good summary for PMC, but here is some explanation:

1. The team is the client, the vendors, the EPC and its own PMC team members. The more the PMC is known and the mote he knows the people involved, the srelationships and synergies will flow smoothly.
   
2. The PMC must know both IT and process. No time for learning curves. 
   
3. Knowing the market from the DCS suppliers all the way to the ERP vendors and whatever is between.
4. Once the suppliers are selected, these should not be unknown entities. Due diligence for new or emerging suppliers must be at least done.
5. Again, there is no time for learning curves here either.
6. The PMC must have ready made templates to use for a project. No time for discovery.
7. Same for standards. More importantly, to know the client standards and best practices.
8. A mutually agreed methodology should be used i.e. Kepner Tregoe. 
9. A Total Cost of Ownership model must be also in place, as well as the ability to calculate and validate Total value of Ownership (benefits) contributed by various solutions.
10. Last, but not least, relationships and people skills boil down to leadership. Interview the PMC members and look for the elegance, communications skills and emotional intelligence know how that it takes to establish a winning team.