Well I have read on this message board that RIRs can be aggressive. I personally had (RIR crossed with RI white) sex linked hens- they are called Golden Sex Links that I sold for aggression toward chickens they were raised with. They stopped allowing my EEs to eat!!!
Your Comets I believe might be the same or similar to GSLs in breeding.
Leghorns have a reputation for cannibalism when overcrowded I have read on BYC. They are going to probably be flighty. I have Cali. Whites which are a cross and they are flighty.
I have some BAs but they aren't laying yet and so can't tell you about them.
Bottom line is, I would recommend a nice roomy shed coop. You can always place your bantams inside a dog kennel in the coop if things get bad, if they free range.
If you are wanting a run and coop setup, I would recommend having a backup plan- the plan for either building a second coop and run for the docile chickens, or selling some of your chickens.
They MIGHT get along great- please don't let this post dissuade you from just putting them all together if that is what you want to do. Just be prepared - chickens have personalities just like people. You can never tell what they will do. Your RIRs might not be aggressive.
It can be especially difficult bringing in new chickens with aggressive hens. So it is best to have them all raised together if possible IMO.
JMHO.
