I can't speak to IPF, but I can speak to PIP.
I had a manager come in shortly after I'd been hired to replace the manager who'd converted me from contractor to employee after 2 1/2 years. The new manager put me in the bottom 10% under the old performance ratings. I don't recall getting an IPF because being in the bottom 10% automatically made me ineligible for the bonus my first year as an employee.
When the mid-year evaluation came along, I was put on a PIP and suddenly I had to try to "achieve its usually close-to-non-achievable-or-purposely-vague goals". Within 3 months, Cisco announced that they were going to offer the early retirement plan of '11 and then the large LR a month later. Suddenly, my PIP's goals became pretty much "just keep doing your job" and the weekly 1-on-1 meetings became pro-forma "Hi, what did you do this past week? Ok, see you next week."
I pretty much knew I was going to be let go, and I was. But, a manager whose team I'd worked closely with knew I was being railroaded, and his first opportunity to expand his team resulted in a call asking me if I wanted to come back. There, the team was a long running stable team that had been together for years with very little turnover, so management pretty much evenly split the bonus budget equally across all of us, with the exception of a slightly higher bonus for someone if they had worked some large, complicated project and performed well.
During my second time around, if I looked in HRMS, it showed my last performance review as being on a PIP since they'd moved onto the new People Deal, so I was forever stuck with a sh–ty performance review visible to the management chain. I received 100% of my bonus all 3 years on that team, including the year I was LR'd for the second time. So, having an average? 1.0 IPF every year didn't keep me from being LR'd.
But, I'd say that having a below 1.0 IPF doesn't preclude you being rehired because many managers will rotate a lower IPF around the team to provide a higher IPF to a team member to fund their higher bonus. You just don't want to have that below 1.0 IPF multiple years in a row. I think having a PIP in your employee HR record is much worse than a below 1.0 IPF, yet I managed to get rehired.
And I'm back a third time at Cisco, but not yet as an employee this time. My most recent team has been very stable and has only grown by 1 person in the last 3 years, and converted 2 people plus the new addition to employee in that same 3 years. Whether my 2nd LR will preclude me converting a third time is yet to be determined, but at the rate they're paying me (25% better than my last employee wages), I'm not in a rush to convert. If I suddenly get let go, I may miss not getting that severance package, but 25% extra pay going into savings for the past 3 years has funded my personal severance package.