[Make-wifi-fast] Best practice: multiple SSIDs on a radio...?

[Rich Brown]

Sorry for this somewhat OT question, but I know that I'm tapping into a mother lode of Wi-Fi knowledge...

A local coffee shop wants a guest and a private network, supported by separate SSIDs. Is there a benefit (or would it be bad) to put the public network on one channel and the other network/SSID on another channel?

(And is the answer the same for their 2.4GHz and 5GHz radios?) Many thanks.

Rich