Thanks. The version of NTP in MATE for RPI is just hosed, it refuses to run at all so I cannot use GPSD with it. Removing timesyncd didn't help either, so I started looking for other solutions and came across CHRONY. I purged all NTP files, installed CHRONY, and then modified my chrony.conf file to read the data stream coming off the USB GPS receiver. If it was a PPS capable receiver, I would've had better accuracy, but it appears to hold time just fine over the course of a night.