. In a scenario like mine—where the aircraft was already above 500 ft AGL, with a strong positive climb rate (more than +2000 fpm and stable)—would it make sense to select Flaps 15 to prevent exceeding the flap placard speed?
main risk with reactive windshear is uncontrollable descent and terrain contact. Increasing speed and strong climb is not an issue. In a windshear a pilot should be too happy with +2000ft climb. To avoid overspeed all he has to do is to just pull up and bring the speed back. This high ROC may even take the aircraft out of windshear itself. Why bother about flap at this stage? On the other hand falling airspeed and descent is a serious issue and tricky to handle. You may have pull back to stop descent till stick shaker and fly with intermittent shaker on and hope gust changes direction to allows to resume climb at normal speed.