Hi Spike and welcome to the forums! In my opinion, the KT1, (and KT2 which is the same), turbo head is really a nice piece of work! I really like it's thick, quality construction and it's nice, thick Pyrex lens. You can also upgrade it with some of SF's most powerful LA's if you want to use it later with different battery configurations.
Yes, as Keith alluded to, it's 2 1/2" wide so it won't be as handy for pocket carry. It throws very well however and will surprise you in fog, smoky and cloudy conditions and even through windows.
The KT1 comes standard with a N1 lamp assembly that many have said is not powerful enough. I disagree in that if you want a nice round beam with the most throw for a Surefire 6V such as your 6P, it is great!
Another benefit to it is that when you set it down on your bedside table, the 2 1/2" width insures it won't be knocked over easily!