When I asked NGK about projected tip plug use in kdxs, they said:
It is highly recommended that you don't use a projected style spark plug in your application. These bikes are prone to detonation and vibration and you would be exposing the spark plug to thermal and mechanical shock. The results could be spark plug breakage and internal damage to the engine.
He said every week he had requests from riders that NGK pay for their broke bikes....broken due to projected tip sparkplug use.
My $.02 (not that anyone asked)..a projected tip plug figures to be about 1/2 step hotter than its corresponding 'regular' brother. The spark isn't any 'hotter' or 'better'...so the improvement to your bike likely is due to the plug staying cleaner.
...which it would with, say a BR7xxx, too...if the jetting was a bit sharper.
Yes I understand the projected tip sticks out further into the chamber and thus may be figgered to light the A/F mixture better. Whatever its advantage, perceived or actual, it wouldn't matter it the tip fell off!