I tried a pair of Pila 150S cells in my Hyper Lux V, and found the same thing that everyone else has.
Measures 1,160,000mcd with 3 CR123A disposables.
Measures 1,140,000mcd with 2 Pila 150S rechargeables.
So it IS a bit dimmer, but not that much so. Not anything you could readily detect with the eye, but it does show up on instruments.