Sorry for the slow response. Ok, I determined my backyard benchmark position using a 24 hours collect using a dual frequency GPS rig. Results are interesting. I did 2 Reach collects, a 10 hr and a 24 hr.
Horizontal Accuracy : 15cm-30cm. This is really good!
Vertical Accuracy: .8m - 1.5m. Arg, not great but still really good.
So what I am seeing from the Reach GPS, with it’s stock antenna, is that it is really good for determining a horizontal position, but maybe not so great for getting a good Z value.
Note: my “backyard benchmark” is not optimally placed in the extreme! I maybe have 10m clearance to numerous buildings and fences, not to mention the overhead electric wires and the nearby forest that is probably 20m away and 20m high!! So the multipath monster is lurking bigtime in my backyard!
In an open environment I would expect horz accuracy around 20cm and Z accuracy solidly under 1m, hopefully in the 60cm range. Something to test later.