The next step up from the standard P1 is the P1-CE, the "CE" meaning that it uses the CREE LED. The CREE LED has significantly higher brightness (watts/amp) for the same drive current than the Luxeon-based standard light, but the diodes are more expensive, and so are the CE versions of these lights.
The ultimate version of the P1 at the Fenix Store is the P1-CE-SE. This is a limited edition (only 50 units made) that uses an even higher grade CREE diode with higher efficiency (brighter still), more neutral white color, and a MOP (medium orange peel) reflector that results in a smoother, more floody, beam quality. I have one of these and it is an excellent flashlight!
I think that the MOP reflector versions are now an option on the regular versions of the P1. You can choose either MOP or polished smooth reflector versions. The smooth reflector gives a slightly brighter central hotspot to the beam which gives it better throw, but the sacrifice is that the beam quality in the spill area around the central hotspot is not quite as bright as the MOP version, and tends to exhibit artifacts (dark rings) that bother the "white-wall hunters."
For the LE version, that comes only with the MOP reflector, the loss in throw in the central hotspot due to the mottled reflector seems to be offset by the brighter overall LED, so you get both smooth, bright spill and virtually no sacrifice in throw compared to the regular P1-CE.