XBEE SI with low freq switching regulator

Hi,

Doc says “If using a switching regulator for the
power supply, switching frequencies above 500 kHz are preferred.”

In the actual project, the regulator is switching at lower rate, such as 270KHz, and there is a 2nd one for another part of the circuit (stepper motor driving).

What can we expect in in that non “preferred” case?
(What do you mean by “preferred”?)

Thanks.

Marc