Wow, impressive results, this is looking fantastic. My guiding graphs when i am well aligned and balanced are 2 arc seconds up and down, which is very similar to your PEC graph.
What is the correction interval (i.e when you are recording, what is the interval of the guiding corrections?)
The reason why i ask, is that based on some research, i have seen that if you are using PEC, it is best to guide with a much longer interval.
i.e The recommendation is around 3-4 seconds, to reduce seeing effects (which works really well for me), but the timing of corrections are based on the accuracy of the mount.
I think if the correction interval of PEC is really small 0.2 seconds say, and guiding is all the way out at 4 seconds. (guide camera timing)
This will eliminate conflicts, because the PEC corrections will be many tiny corrections, continuously.
Then guiding corrections really, fix anything in the >1 arc second range due to other factors, etc.
It would be really great if you could test this and record the outcome again.
I suspect this will get your graph down to max 1 arc second each way.
i want to test your PEC approach, once you are confident, could you let me know with some detailed notes.
Also we should contact Jaseq so that he can promote your changes into the driver for Nightly.
This way we can get a broader range of testing from CEM 60 / 70 and other mounts.