The SF optics in the E-Series and L1 does a phantastic job. Maybe that's the reason why they use it? I have yet to see a reflector being able to achieve such a beam in a small E-Series head and in lightweight plastic.
Cree LEDs work perfectly with reflectors. Don's Cree adpated reflectors do produce the most desirable beam of a LED/reflector combo I know. They are widely used in mods on CPF.
Almost all the optics that came after the NX01 and NX05 in 2002 were made for the lambertian distribution pattern. Until the Cree and SSC LEDs hit the market, that is.
The NX01 and NX05 were made for the batwing LuxI.
bernie