If things have changed since early 2006, I might consider getting the new 6P LED.
The Cree LEDs that power the 6PL weren't announced by Cree Inc until Feb 2006, so I find it unlikely that you saw a Cree LED. Shot Show 2007 was where they were really showing off these lights for the first time. They might have had a pre-production prototype, but it most likely wasn't a Cree based light because they have only been shipping for the last 6 months or so.
The LED conversion kits just plain suck rocks and are near-worthless, IMO.
I assume you haven't used some of the newer ones then. The Gene Malkoff kit uses Cree emitters, and puts out over 100 lumens for nearly two hours, with decreasing output until the 3 hour mark. I have one in my G2Z it has a light pattern better then the L5.
At that time, the 6P incandescent & 6P LED were out and had close output specs (60 vs 80). A side-by-side comparison of both with fresh batts did not favor the 6P LED for effective use...
I remember a Coastie telling me that he loves his 6P Surefire, but the run time sucks (he's searching a ship which can take an hour or more). They have similar reflectors so the throw is the same, the only difference is the color spectrum, which isn't that big of a deal to begin with, and LED colors are closer to daylight colors.
With the 6PL you get 10 hours of light vs 1 hour, with the L5 (or you can put a Gene Malkoff in your 6PL) you get 3 hours of 100 lumen light vs 20 minutes with the 6P and the high output bulb.
When Surefire starts selling the P60L bulbs (thats the LED that is in the 6PL and the G2L), I will be getting one for my G2Z, that way I got a 10 hour light for when I need longer run time, and I have the Gene Malkoff for brightness, the same way I can drop the two assemblies already in these lights.