almost equal.
the reflector (a good one!) looses some :thinking: 10% of light + the front glass loss (another 5-10%),
any media transition looses about 3-10 % (depending on material) and an optic has 2 of them + the internal reflection loss
at least, since switching to good reflectors its my impression that optics are way worse. Even if they are not, its inside the head. Seeing all that area around the emitter being lit with an optic but dark with a reflector, is my reason to use the way cheaper optics in less important lights only, f.e. town bike tri-Cree:
this one gets smoked by my single Cree with McR-XR 19 mm reflector, but the dynamo only gives some 500-550 mAh to the triple, while the modded light pushes some 900 mA to the single cree.