I have been using the Here + RTK system for large area survey for around 6 moths now. And I have accumulated a good sample size of how well it is working.
Currently, on ArduPlane 3.7.5 the results are better in the x and y plane but not much better than a regular GPS in the z plane.
I have mentioned in a post here before that I don’t think the correction data is being applied to the GPS records in the Cam Logs. But found it difficult to confirm this.
So I went through all my flights and created a table of accuracy results comparing the vertical accuracy of the Here + RTK to the eBee RTK and a then a regular GPS unit.
These are samples over time from the last 6 months, all flights use ground control to calculate the mean vertical error.
I have tons of data .log and quality reports I can share, Unfortunately, I can’t release all that data to the Public domain as they often are from sensitive infrastructures assets like Gold Mines and Power stations.
Here is a link to the comparison table
https://docs.google.com/spreadsheets/d/1i3t_v2x8GuCC0_EU4I0UFD8kHV6zpmTHFxa24P9T-u4/edit?usp=sharing
For those that can seriously help I can share .log images and QC reports with you Directly.
I have since become aware that Release 3.8 may possibly fix the issues I have experienced. " - much improved RTK GPS support"
However, I will leave this post here in case it helps the developers or anyone else.