Sorry, I do not have a solution, only another problem that I will add here. I have been fighting to get my dual extruder working for a long time. I have gotten it to the point where it can print, but the Z-axis does not move properly. After dropping to the low stop, when it should raise to the nozzl...

I would think for R/C your #1 concern is weight. The specific gravities are: ABS=1.05, PLA=1.25, PETG=1.38. I suspect CF or GF raises those numbers a little, but shouldn't the main comparison be strength-weight ratio?

If you are game to try more filaments, you might want to try GF-PETG. I have not used CF-PETG, but have tried several other CFs. The GF is much shinier with other differences, too.
BTW, I would recommend using a steel nozzle for any filled filament.

I tried to upload this video, but it must be too large. https://youtu.be/exFbOX4EDJM
Shows the huge difference between flexible filaments. How does Semiflex compare?

I thought this one might qualify: https://www.thingiverse.com/thing:421542

Vandal968 wrote: My printer has been running 24x7 for the last few weeks getting ready.c

Are you printing samples or parts for sale on the floor?
I am not going this year, but hopefully next. I am a licensed Class 3 NFA manufacturer.

zemlin wrote:I do plan to spend more quality time on two-material printing - the early test prints I've done were impressive (PETG with PLA support). .

Do the two stick together, or does the support come off without so much as a click?

I had already decided to try using a 50% infill for that purpose. I will let you know how it works. There are a lot of MakerGeeks (?) filaments that are down in the 40A durometer range. Those would be spectacular for this. They're a mixture of PVA + foam, and the PVA is dissolved out after printing...

Most likely a CPU failure. I had a different, (non-M2), printer die like that. I replaced the CPU, and it works fine.

I had already decided to try using a 50% infill for that purpose. I will let you know how it works.