In most every school, P/F or letter grade, students help one another out. I go to a school with the traditional system and during the first 2 years, there was lots of stuff from many different people sent out over the listserve. People were willing to stay late to help one another out. Come to think of it, even during clinical rotations (also letter grade), we have an online file sharing system that is full of guides and reviews. Same goes with friends I know from other traditional schools.
Secondly, every school has gunners, you just don't know them. Gunners may not actively try to harm your grade, but they will be the ones getting 95+ on every exam without most people knowing.
Thirdly, even though your actual grades from the first 2 years matter little for residency apps, your class rank does matter. So while you may have that false sense of security that P/F is like a tremendous weight off your shoulders, the internal ranking system, which will be based on your numeric grades, will most likely go into your MSPE (aka dean's letter). There are very few schools that have a completely rankless P/F system (Yale and maybe Stanford come to mind). True, 3rd year grades/evals and Step 1 are the two most important factors for residency, but class rank is pretty high on the list too. I hope for your sake that you're making better-than-passing grades with the more-than-undergrad time off you have.