think as a reflector as a diamond on a ring...as each angle of the reflective metal is called a facet just like on a diamond ring....the more facets on a ring equals more mula as it it sparkles more due to reflection from the light...well that is the same as the reflector as the more facets on a reflector actually reflects more light into the tank.
is it worth it spending the money in my opinion yes...i have owned spider, lumenarcs and lumenbrights and in personal experience lumenbrights are the best of the three as you are getting the most light back into your tank from the metal halide bulb