First, I'd like to acknowledge that this topic is being discussed in this thread; however, since the conversation got sidetracked into dough hook oxidization, I thought I'd start again.
I am a new Bosch Universal Plus owner who bakes bagels. I am mixing 106 oz. (6.6lb, ~3kg) of dough at 51% hydration in the Makrolon bowl, and I am having the problem that DanS7 described--the dough is sliding around the bowl with the dough hook rather than being kneaded. In the meantime, the friction of the dough against the bowl is causing my dough to overheat (although I can adjust for this with my water temperature).
I'm aware that the mixing action of the Bosch is different than my old KA, but I'm primarily basing my observation on 2 things. 1) The motor load, based on auditory clues: I took the bowl off completely, and compared the motor sound vs. the sound of the dough hook pushing my dough around. I can hear whether the motor is under load or not. 2) The fact that after 10 min. of mixing, the dough is underdeveloped.
So far I have tried mixing the flour until it is just incorporated, then giving it a 20 min. autolyse; this helped, but not completely. I have seen a suggestion to increase the hydration of my dough, but I thought I'd ask for other opinions first.