I also have the Nav Pro. I agree it's difficult to actually justify the extra spend, but I'm glad I did as I know I'd want the bigger Nav screen unit if I had gone with the standard unit.
For info - here are the main extra features over and above the standard Nav units
- Bigger 8" TFT Screen
- 2 SD card readers (available all the time as the maps are stored on the HDD)
- Dual DAB tuner, podcast
- Dolby Surround/multichannel capability
- Video file display
- SSD 64GB
- Memory/Jukebox music recommendation/MLT
- 3D detail map, 3D map supplements,
- 3D landmarks, 3D city model
- POI online search, satellite maps, multiple maps
- Gracenote database
- Maps in 3D topographic presentation (bird's eye view) with buildings depicted
- Navigation data stored in the internal memory
- Points of interest, featuring pictures, accessed using the SD card
- Telephone contact/address data can be used for entering destinations in navigation system.
- Traffic sign display (if Lane assist specified)
- Picture viewer (JPG viewer)