Thanks for the insight Jehan, it's much appreciated.
It seems FhG recommended no SBR at the time to remain compatible with pre-iOS 5 phones, since iOS 4 didn't include SBR. And the sampling rate recommendations are certainly in there, although I maintain 48KHz is a better choice for pro compatibility. Do you think it's reasonable for standard Linphone to offer these as options? Or maybe we should build our own pro-grade version?