[time-nuts] Comparison of Ashtech Z-12 and Z-Sensor for timing purposes?

[Stan]

I am looking for a GPS receiver to provide high accuracy, low jitter timing
pulses in my lab. I have found an Ashtech Z-Sensor for sale but cannot
readily determine from the spec sheets how it compares to the Ashtech Z-12
in terms of position and timing accuracy when used as a static, standalone
receiver (no DGPS, etc.). Can anyone give me some insight? What are fair
prices for the Z-12 and the Z-Sensor? What options should I be looking for?
Finally, are there other receivers that would be better suited to my needs?
Thanks!

Stan