DHCrocks,
The KT2 for three SF123A models has the N2 Lamp. It is rated at 105Lu/60min. The MN16 225Lu/20min "High Output Lamp Assembly" (HOLA) will also work in the KT2 TurboHead.
A gentleman who goes by the tag "new-arguy" on various forums posts these two photos to help show what TurboHeads do to the beam:
MN11 225Lu/20min "HOLA" for M3 Bezel:
MN16 225Lu/20min "HOLA" for M3T TurboHead Bezel:
The larger diameter reflector of the TurboHead concentrates the same amount of light into a tighter, more intense beam giving you the ability to illuminate targets at longer ranges then a standard bezel can.
I have a few TurboHead models and think they are well worth it.
Nerd,
The N62 gives you 12 minutes of runtime on a set of SF123As.
However, the batteries are over-driven so hard that they heat up. If you are using the N62 constant-on (This is not what the N62 is intended for), then the batteries will over-heat and shutdown after about 3 minutes. "Thermal Shutdown" is temporary and the batteries will work again once they have cooled.