I'm late to party on this as you seem on the right track.
Until the Lumenarcs with the faceted angles showed up around 18 yrs. ago everyone had those lame built in reflectors that allowed most of the light to be lost and not aimed down into the tank. Lumenars and the many copy dome reflectors made later became one of the revolutionary improvements to keeping acropora.
I haven't run MH for about 9 years but assumed no one ran MH without a quality dome type reflector. They are a must have not only for improving par but also to have consistent coverage across a very wide range.
Until the Lumenarcs with the faceted angles showed up around 18 yrs. ago everyone had those lame built in reflectors that allowed most of the light to be lost and not aimed down into the tank. Lumenars and the many copy dome reflectors made later became one of the revolutionary improvements to keeping acropora.
I haven't run MH for about 9 years but assumed no one ran MH without a quality dome type reflector. They are a must have not only for improving par but also to have consistent coverage across a very wide range.