I agree with everyone about the PPI and it seems you are aware of the IMS issue. Here are a few things that I missed when we got our Boxster...
- Make sure the key fobs work and lock and unlock the car properly
- Make sure the windows drop and go back up when opening/closing the doors
- Make sure the windows drop when you unlatch the convertible top
- Make sure you can put the windows back up after you shut the convertible top
- Make sure there are no horn beeps (single or double) when you set the alarm
- Make sure the center console door hinge isn't broken
- Make sure the plastic around the side view mirrors and interior door handles are in good shape (a lot of people didn't go to Porsche for maintenance and a lot of the plastic clips can be broken)
We bought a mechanically sound car but needed to replace door latches, etc. to get the micro switches working (which added up to a lot of money). Good luck!