A fork mixer will not heat up your dough in the mixing process. A fork mixer has a free spinning bowl and a two pronged agitator that can run at both slow, and fast speed. It is gentle on dough as it mixes, but the mix times are longer when compared to a spiral mixer. But because of the gentle action on the dough, this will help you manage the dough temperature, and achieve your goal temperature. This will result in a higher quality dough that is not heated.
The double arm mixer was one of the first electric mixers. It mixes gently and slowly, which essentially copies the motion of hand mixing. Because the agitation is gentle, the resulting dough is very close in characteristics to that of dough produced by hand mixing. Not much time will be saved in production as it is a slow mix..