Wasn't there a very recent thread on the current situation with FAA on their automatic filing of airspace violations based on radar detection? Where they made clear that the radar detection could be well off the GPS position and they emphasized at the old advice from real VFR-without-GPS-times to stay clear by 2 miles form airspace borders?
Personally, I did scratch close to airspace borders right after PPL, relying on iPad and GNS - BUT after a while I realized that this is neither polite to relevant ATC and/or other pilots. At about 300h I had one nearby occurrence while being close to a CTR and that was quite critical due to the nearby airspace - which I could have vastly ease by simply stay out a little bit more. So, I now try to keep 2 nautical away from these airspaces where possible, to relax controllers, me and the others around.
We do have a mix of WAAS/EGNOS-GPS, non-WAAS-GPS, iPad-GPS and visual flyers out there and we all are thought to take care of each other.