February 7, 2013 at 8:59 pm #21161
The only major downside to the IMP is when their server “cloud” goes down you lose your GMT time.
As for the Ultimate GPS, we had “chicken wire plaster” in our homes and the the reception of the GPS signal was stopped dead in its tracks. So we had to purchase the active GPS antenna Adafruit provided for the GPS.
Having multiple precision clock sources does help alot.