You write: "NASA's advisory board on Mars exploration, MEPAG"
We are not roadmapping. That is a term reserved for a specific NASA function. We looked at and evaluated NASA's notional architectures for Mars exploration. Rather than call them roadmaps call them architectures.
My thanks to Dr. Mustard for the correction.
The journal Nature has also printed a very brief comment on the proposals discussed in the last MEPAG meeting. They note that NASA and ESA officials are now looking for ways to launch NASA's Mars Science Orbiter (to pinpoint methane sources among other scientific goals and provide data relay for landed missions) and ESA's ExoMars rover on the same launch vehicle.