I have a 6-quart "Professional" Kitchenaid. I seriously doubt you will be able to do 10 loaves in that thing but maybe you can do 2 or 3 batches. I guess it partly it depends on how big a loaf you're making, but the most I've ever done in mine is 2 big loafs so I'm guessing with a bigger bowl you could do 3-5 loafs at a time.
I don't think the mixer really saves that much time over doing it by hand but the big benefit is that you can do other things while it's mixing, and of course you don't have to do the physical labor. When I'm making bread I usually do 90% of the kneading in the mixer and then finish it by hand so I can make sure it's good to go and make any final flour adjustments if needed.
One thing to note if you're switching to a stand mixer is that you might have to fine-tune your recipes. When kneading by hand the dough tends to pick up a little extra flour from your hands, the tabletop, etc but that doesn't happen in a stand mixer so I usually have to add a little extra flour up-front. On the other hand the plus is that once you have an exact recipe for the mixer (ideally measuring the flour and water by weight) you can be confidant that it will come out exactly the same every time.
I will also say that I think the mixer will probably NOT be good at small batches. Even my 6-quart model struggles if I'm trying to beat just 1 or 2 eggs. There is a height adjustment to fine tune the bowl height which helps the attachments get to the bottom of the bowl without hitting the sides but I still find that for small batches it's not really worth it. I imagine the problem is exacerbated with an 8-quart model.
Overall though I think a stand mixer is indispensable for even semi-regular baking and I can't imagine running a commercial kitchen without one.
