So, as a proposed methodology, how does this sound:

Determine a reasonable ballpark figure for typical codec and jitter-buffer delay (one way). Fix this as a constant value for the benchmark.

Measure the baseline network delays (round trip) to various reference points worldwide.

Measure the maximum induced delays in each direction.

For each reference point, sum two sets of constant delays, the baseline network delay, and both directions' induced delays.

Compare these totals to twice the ITU benchmark figures, rate accordingly, and plot on a map.

- Jonathan Morton