Had a little spring fun with my 300 and 1.4x TC this morning.
840mm equivalent. Powerful weapon, but surprisingly easy to use.
Even with the limiter set there was a clear drop off in focus speed (EM1 mk2 with latest firmware, lens not), but not accuracy.
All the images above were processed with C1 and in some cases ON1 No Noise, just to see and in each case I compared the image to an ON1 RAW 2021 version that did not compare well (both less sharp and noisier, but possibly still better than LR). I am going to wait and see how the 2022 version goes, considering the obvious benefit of ON1 No Noise, but so far C1 is still the one to beat because the base image is just better.