I'm just a 3P, so take this all for what it's worth.
When I was going through Primary, most of the P-3 IPs I met were pretty cool, and had good things to say about the community despite having gotten shafted by the advent of HONA (Health of Naval Aviation, which puts a restriction of the number of flight hours each aircraft can fly based on a complex equation involving airframe age, the probability the wings will fall off in flight, and silly things), which cut their flight time down into the hundreds of hours for an entire tour vs. the thousands of hours guys had been getting prior to that. This meant that it became much harder for people to become PPCs because you need at least 700 hours of total flight time, which typically works out to about 500 hours in-model.
Now, you take a bunch of aviators, then keep them from flying. Add realization that without as much experience, these pilots are going to need to know even more about the aircraft to offset their lack of experience, so total knowledge of all of NATOPS, down to a genetic level, becomes standard. Couple that with the fact that the aging plane is starting to exhibit symptoms that were never covered by NATOPS, so not only is NATOPS a requirement, but so are several other publications (HAZREPs, Job Aid, Blue Brains, FE Job Aid, P-3 Digest, etc.). This sets up a highly demanding environment where your systems knowledge, while still secondary to your ability to fly the plane and your general pilot knowledge, becomes nearly as important. People get very nit-picky and quiz you all the time, in other words.
The final piece of the puzzle, from my perspective, is the advent of CMO (Combined Maintenance Organization). One paper, it makes total sense: with fewer aircraft due to red-stripes, there's not as much of a reason to have individual airplanes assigned to each squadron, so a single, wing-level maintenance organization divvies the planes up to the squadrons as they're needed. What this does in reality is reduce the power of the individual squadrons to do things their own way, as well as taking away lots of the jobs JOs had in maintenance since maintenance is its own command, separate from the squadron. Since we can't have guys without jobs, new jobs get created to fill the void.
So to finish answering your question, the P-3 community is indeed pretty small; I've already run into three or four of my friends I went through Advanced and the FRS with out on deployment. The Navy itself is pretty small too, though--I've also run into guys I did middie cruises with my senior year out here too, and even my roommate from the Naval Academy Summer Seminar, of all things.
This is probably far too much information, but I'm bored and trying to get my sleep schedule turned around for this week.