Coolant changes in the MB maintenance system, like brake fluid changes, are not part of the mileage/time scheduled maintenance tasks. They are considered separate tasks, and the change interval is purely time based regardless of mileage. Based on the information previously posted that Zerex G-05 is the same as MB coolant I would suggest you use either this or genuine MB coolant, even if you have to provide the antifreeze.
The pH levels of conventional and organic or hybrid inhibitor package antifreezes cannot be directly compared. Conventional inorganic inhibitor antifreezes are formulated to be alkyline, and there are test strips you can buy to test the coolant's reserve alkylinity. Once it reaches a certain level the coolant should be changed, however, these test strips are not valid with Dexcool (not sure about G-05) because they are not formulated with as much reserve alkylinity due to their completely different inhibitor chemistry.
The synthetic oil crowd has likely not picked up on these new antifreeze products because they haven't been around that long, and they haven't been marketed that aggressively with heavy advertising expenditures.
Since my current cars range in age from 12 to 40 years and don't see much annual mileage accumulation, I'm more concerned about internal corrosion than mechanical wear, which is why I now use Dexcool and change it every two years, even if the car has little mileage accumulation, and I change the coolant and brake fluid at the same time since they are both on two-year service schedules.