I have owned a P-mod now for 2-3 months and love it.
I've got large diaphragm mics so the warm mod was a no-no (unless you like really muddy recordings) and felt the I wanted a little something extra added to the mid/upper end of the sound spectrum so Transparent also was not considered much. That left the Presence mod which does bring the recording a little more up front and alive, at least IMHO.
The only comparison I ever did was I listened to
ALL the soundclips that the Oades had on their website for days. I just wish they had used mics that were a little more common so I could have got a better idea of the sound differences beforehand.
As to why there don't seem to be as many around, don't know. They are a tiny bit more expensive then the other 2 mods, maybe that had something to do with it?