A few points:
1. You indicated you did not do a side by side with the IF and Panny. You probably would notice differences more during a side by side.
2. As others have mentioned your screen is relatively small at 80 inches. The larger the screen the greater the differences.
3. Resolution is not everything, however, it sounds like you like the Panny with 1080 better. Black level, contrast, color, brighness, sharpness, etc. all combine to provide a better projector.