If your neighbors wouldn't like a rooster, I would shy away from toms. Roosters are a bit more attention grabbing, because they are higher pitched, but toms will gobble in response to other noises. For example, a roo crows when he wants to and if he hears another crow. A turkey gobbles when your neighbor gets home and slams their car/house door and when they yell at your birds to shutup.
Now, that being said, I think you could easily get away with turkey hens. The loudest sound my hen makes is a "Pip.. pip.. purrrr" and it could easily be passed off as a song bird, or other wild bird.
As for keeping them with your chickens. I know many people do, before you decide you should research and see if Blackhead it prevalent in your area. SandSPoultry keep their turkeys with their chooks, and I keep the hen I bought from them with my chickens and everything is hunkdorey. The ONLY problem I have had keeping them together is the turkey hen will roost top rung and we went through a spell where she would jump down and land on unaware adolescent chickens and would squash them. I know it wasn't intentional, but I lost several adolescents that way, so we moved her out of the coop and into the yard where she lives happily with the freeranging roosters. She actually protects her two roos from the geese. LOL
-Kim