Did a little more GPS test.
I think to purely test the strength between GPS receiver between your two devices, I would recommend "GPSTest" app in the market.
Then let's
1. Disable all data connections (put it into airplane mode)
2. Only enable GPS
3. Put them side by side at an area covered by GPS satellite
4. load GPS Test and press Start from option menu.
You can compare
SNR value displayed from both devices to see the performance of their GPS chips.
Note: PRN here means the number of Satellite assigned to the tast. SNR is signal-noise ratio. The higher the better of course.
Because GPS signal is one thing, Maps is another. So Google Maps/Navigation apps need data connection otherwise they cant process data received by GPS chips and put into a user-friendly map.
Some reference links:
http://www.gpspassion.com/forumsen/topic.asp?TOPIC_ID=6105
One discussion thread in other xda forum about GPS testings:
http://forum.xda-developers.com/showthread.php?t=750945
Hope it helps.
btw, if you don't have a 3G/4G plan, in outdoor where wifi is not available, the stock nagivator will NOT work. There are , however, some "pure" GPS apps in the market you can google about them, which requires only GPS connection since maps are already stored in those apps.