In 7500 hours of tubine helo flying, I never had a hot start, mostly because I never pushed far enough to get one. Flat accel from a dead battery, or poor start behavior (perhaps due to dirty nozzles) are detectable prior to things getting out of hand. Unless there is something wrong with the fuel control, the engine will not jump to crazy temperatures unless you let it hang, or open up the throttle with too little N1.