No idea about Nippon piston compression height. The OEM P29/PM7 is supposed to be .040" in the hole at TDC I think... which comes out to 1mm. If you raise the piston surface a whole millimeter, you'll raise the compression quite a bit. If the compression is listed to be the same, maybe the pistons have a lower dome and a higher crown- which would be better for more even combustion.
As far as static compression goes, you could realistically go to 12:1 or even 13:1 on a daily driver if you have the cams and the tuning to support it. When your static compression goes up, you need to go to larger cams (longer duration, more overlap) to bleed off some of your static compression. By doing that, you still reap the efficiency gains of the higher compression for more power plus you get the breathing benefits of the bigger cams. All this combined with really good tuning = great power.
FYI- I ran several engine builds at higher than 12:1 on pump gas in a daily driver. No problems for me, but I spent a LOT of time tuning the car. I also had access to 93 octane, but 92 didn't ping.