I'm really happy o see your progress on this, Dan. That is a nice looking board.
Looks good, so far. Now onto the "fun" testing regime.greg, w9gb
Interesting Tech Note, regarding Motorola receivers and backup battery usage.http://www.synergy-gps.com/images/stories/ShopTalk/9backup_battery_considerations.pdf20 years ago, that was important fir Almanac retention. The modern uBlox module likely performs that step internally.
I have the microcontroller configure the U-blox at each startup, so it should always work from a cold boot. I may still put a supercap on there, but it would have very limited usage. If the GPS receiver goes down, that means the entire box turned off. And you will always be limited by the warm up speed of the OCXO. The u-blox is very quick at locking to GPS.