Re GPWS .. this came a long time after the segmented takeoff approach (ICAO PAMC dating back to the 50s as I recall) so the two are not integrated unless the performance engineer considers the GPWS envelope in designing the escape procedure. If, for normal AEO departures, which are way above the OEI profile, you get a warning, then you most likely will do so OEI as well. No reason why you can't draw this to the attention of your ops engineering folks so that the departure can be reviewed for a less stressful pilot experience OEI.