I have have owned guineas two years come March. Raised most of them from day one with my chickens. The males do chase the chickens and pull tail feathers. They live for the chase. They love when I chase them around the yard. The female guineas, for the most part, are mellow, but loud. There is one ornery one who likes to walk around picking fights with my more agressive rooster. He is very gentle with her. My run is multileveled, so the guineas patrol the ground and the chickens stay higher up. That is until afternoon, then the guinea males calm down and everyone is on the ground.
One thing that was annoying about raising them together is that the guinea keets like to peck toenails, especially on birds that have blue legs. Though they will peck eachothers toenails too. They may even peck them till the bleed. Also, I constantly had to wash the guinea keets' feet because they were not as good at cleaning them of any fecal matter they stepped in. It would harden around their toes. (I'm talking about the first few weeks of life)
As for feed. I did one round of 2 guineas with high protein feed. They grew very very fast. I've never grown turkeys, but I imagine that it would have been similar growth.
The second round I raised on organic chicken feed. They have had very slow gradual growth and are still small like my chickens.
Now I have noticed that the ones from my first batch were of poorer health than my second batch. I lost one to sudden death (I think a mushroom accident, though she was way more docile than any I have had since, so maybe there was something else going on.) The other one, male, has had pain in his feet and has grown calluses between his back toe and pad. I called a vet out for it, but no suggestions. He also developed a breast blister over time.
The second batch raised on the chicken feed are very energetic, fly often, have no feet trouble, no breast blisters and make life look easy. My personal opinion is that the higher protein made a better meat bird and the chicken feed made a healthier bird.
However, despite the problems of having the two species so closely tied, I am happy that I did it.
The guineas appear to see hawks when they are far higher up in the sky than the chickens normally detect. One of my female guineas will give the warning cry and I have to stare at the sky for a while before the hawk circles low enough for me to see it. The chickens heed the signal and the guineas heed the chicken warning signals.
My guineas and chickens are drawn to different bugs and different weeds. However, since they cohabitat they have taught eachother to eat foods that the other would normally not eat. For instance, there is a wild grass that grows along the side of my house and puts up seed heads. The chickens learned how to eat the seeds like a corn cob. The guineas watched and started eating them this way too. The guineas learned how to thresh the wheat growing in my yard and taught the chickens. The guineas prefer sow thistle and the chickens collards. Now they both eat both. Just a couple examples.
This year I let a chicken hen sit on a small clutch of chicken eggs and a guinea hen on a clutch of guinea eggs. They were too young to be moms, but they were both desperately broody. So I let them.
When the first chicken egg did an external pip the chick inside started peeping, the hen abandoned the nest and sat on a different nest. I tried to put the egg under her but she would immediately leave and wanted nothing to do with it. At a certain point my dominant male guinea came over to me and started making concerned unhappy noises.
I took the chicken egg and put it under the broody guinea hen. I check it after a half hour. She had it completely hatched and was very protective. They bonded. The next day the chicken hen realized what had happened and wanted her chick back. She squeezed herself into the guinea nest. Both the guinea hen and chicken hen have been coparents ever since.
That chick unfortunately was the only one to make it through hatch (nest accident caused by chicken hen), so he (my new little cockerel) has been spoiled rotten by his two mommies. Neither species would mess with him.
I'm curious how it will turn out long term. I haven't seen any posts from someone who let a guinea hen raise a chicken. He is 5moths old now. Handsome young man just learning to crow. His guinea mom still tucks him under a bush when there is a hawk in the sky... He is twice her size.