I recently acquired a Scorpion LED.
The electronic circuit inside is a buck regulator. I tested to be in regulation from 4.5 to 7 Volt.
Two RCR123 in series may damage the circuit. I haven't tried above 7 volt, since the V/I curve is not linear anymore.
A 168S (or 17670) fits well in the Scorpion LED, but the circuit will not regulate anymore. With a Li-Ion 17670, it starts at almost the same brightness of 2 x 123, but it decreases as the battery is drained.
The Scorpion switch is a "forward" clickie, but it is difficult to activate trough the rubber protection. The Scorpion will not stand in candle mode, even if its bottom is flat.
Hope this helps
Anthony