All true but I think our original poster was probably refering to an aircraft that had something less the "enhanced" GPWS. Keep in mind that most of the new aircraft your either in in the bro mode. or RA mode and you cannot set your RA for any type of alert. The classic's don't typically have that configuration. Setting the RA for say 300' is simply another tool that the professional can use should he want. No harm no fould assuming it is approved by the operator and briefed prior to the approach.