The 6P LED is a solid light, the KT1 does not use an LED (it's a similar bulb as what is found in a standard P60 module, just on a different module and in a huge reflector), so installing it would negate the extended runtime benefits of the LED.
Most people here would suggest that the SureFire turbo heads are just a bit too bulky to be worth it on the smaller bodied lights. It converts a 6P from something pocket-able to something, well, cargo-jacket pocket-able. And just doesn't provide a large enough boost in useful performance to be worth the substantial size. Save turbo-heads for longer flashlight configurations.
The 6P is an excellent platform to start with if you plan on sticking with CR123 cells. You can adapt a 6P into just about any light you want in the future. With extenders and turbo-head it can be sortof like an M4 (minus shock isolation), with an adapter and extension, sortof like an M3, with nothing more than an extension, a 9P. It can be made a throwy LED light with a malkoff drop-in, can be made a multi-mode LED with an alternative drop-in, can be kept stock and enjoyed for a lifetime. it's really up to you
if you are inkling towards recharge-ability, the 6P is not necessarily the greatest starting point. Look for either AA powered LED lights, or 18650 li-ion powered incan or LED flashlights.
Eric