I used the -10dB gain from the "beam" information. That corresponds to the green "dots" on my previous map, which looks like it covers slightly more.
I always interpreted the signal strength maps with -10 dB as being the point at which one should be able to get a reasonable signal with Dish's standard dish i.e., a D500 or D1000. Outside the -10 dB area, a larger dish would probably be needed. In the case of Ciel-2 at 129 W, one may want a separate D500 dish pointed at 129 W outside of the -10dB area. Based on the downlink maps that have been posted for Ciel-2, I don't see the need for a bigger/separate dish for much of the area in the Western Arc.