I understand the noise issue, and the reasoning behind wanting a smaller flock... but smaller flocks of Guineas, in a situation where other poultry are kept on the same property doesn't always work out. Some have no issues, some have nothing but issues. Every situation is different, but it's always a good idea to go into raising/keeping Guineas with your eyes wide open.
That being said, yes they can get along fine when free ranging if they've had plenty of side by side (separated by wires) exposure... but male Guineas tend to lose their minds when their hormones flair during breeding season. Not all do it, but it's a common complaint, especially with just small flocks of Guineas. The more Guineas you have the more focused they stay on each other, and then they leave the chickens alone (... usually).
Sometimes if they aren't exposed to each other enough before they are free ranged together the Guineas will see the chickens as "newbies" or threats to their flock and pecking order and won't accept them at all, ever... and so you may end up needing to free range everybody at separate times, at least during the breeding season.