I'm guessing here, but I think that the two variables that most often account for c1/c2 error rates in addition to media/drive compatibility are:
- burning drive temperature
- burning drive vibration
The drive itself houses a laser that needs to calibrate to certain intensity of 'burn'. The chemical properties of the dye should probably not be that much different even if the temp delta is 25 degrees, but it's a possible contributing factor.
Another thing where the temp rise may contribute are the tolerances for the laser/pickup/servo controls. Heat based expansion could change the tolerance of some parts a few nanometers here and there, resulting in a higher probability of errors
Another possibility is vibration. The servo mechanism has to be quite accurate and when burning at speeds of 48-54x the vibration is already quite high.
Properly fastened and damped drive might be able to perform better than a drive that is lose.