Hello Scott,
Please note that any ESTIMATED accuracy reported by any GNSS receiver remains an estimated accuracy. It is not the absolute truth and should be an indication of how well the receiver is more or less behaving in a specific environment.
Different manufacturers will handle estimated accuracies in different ways in their algorithms. Therefore, I suggest you take your receiver on a survey monument, first in clear view of the sky, and compare estimated accuracy vs true location. If you can repeat the same in “non-ideal” conditions (light canopy, or light or moderate urban canyon) then you’ll have a clear picture of how the receiver’s estimated accuracy compares to the reality.
Last, also note that, as a rule of thumb (and this is valid for any GNSS receiver), vertical accuracy is usually 1 to 3 times less the horizontal accuracy. For example, if you are getting 2cm accuracy horizontally, your vertical might be anywhere from 2 to 6cm.
Best of luck,
JY