Just an opinion but unless you're getting off road plenty or really fancy the look, I wouldn't bother. The headlamp is a bit crap as it is without reducing the throw and intensity any further - and that's with a decent aftermarket set of bulbs. I ride very dark, rural roads covered in crap and need all the light I can get. In the last 20 years I've never had a stone smash my bike's headlamp*.
*clearly I'm tempting fate here...