Generally I have seen servo connectors as being rated to 3 amps continuous. I have seen some saying they were good for 5 or 6 amps. So a cable good for 5 to 7 amps is, if anything, rated higher than the connection. There is a voltage drop across any connection under high current loads as well.
I have used the .35mm2 cable for years in my planes. I make my own as the weight of the insulation on other cables adds up to a lot of weight. I also eliminate the connection at the servo end when possible. I cut the servo leads coming out of the servo as short as possible. I have yet to see a high torque servo lead that was thicker than the servo extensions I make.
AEHaas