If the RF switch should be enabled whenever using WiFi (and not just the external antenna) it’s odd that the Seeed wiki doesn’t state it explicitly. I recall they only mention you should do it for the external antenna.
It would be good if Seed Studio released the final schematic (without crossed-out components) and positioned themselves about this.
I wanted to upgrade to the C6 from the S3, but the WiFi connectivity has proven to be very unstable (I don’t know if it’s a problem with the antenna configuration or something else).