In our project “Doomsday Atomic Alpha Clock Five Project” we also used the Ultimate GPS, along with Wifi and a WWVB Atomic Clock.
The Ultimate GPS proved to be very sensitive but we also added Adafruit’s active remote GPS antenna.
For auto DST, we used an internet projected 10 year table for DST time changes. This way, with no GPS signal, the
clock knows when to change on the projected DST date. We had this luxury because we used a pre-processor
Teensy 3 ARM stamp.