I don't have the P2D, YET, but I can comment on the P1D.
Pros:
Slightly more throw then the P2D
Slightly smaller then the P2D
Cons:
The UI is dumb. It goes Med, High, Low, Strobe, SOS. Why have a low if you're blinded from the Med and High levels. And why have a Strobe if you have to go through 3 levels to get there. If the P1D's UI was Low, Med, High, SOS, it would be much more useful.
It has a twisty. Twisty's are ok if you don't use the light much, or leave it on for a while, but if you're playing, just want to get quick light or want one handed operation, it's cumbersome.
It's more expensive.
Bottom line:
I can't comment on the quality of the P2D yet, but I don't see why anyone would buy the P1D over the P2D. After getting the P2D, I'll keep the P1D as a backup.