Tumbleweed Farm, I agree w/ Fred as well as the previous poster. Only 8 hens and 3 males is just not going to work. Even if they were same age, raised together, etc. & the pecking order was well established-there would still probably be serious bickering. For 8 hens, you should have 1 or MAYBE 2 cocks, no more. Frankly, 2's probably too many & 3 or more is just asking for problems.
In answer to your question, I would move the offending barred rock. If you temporarily move the Sussex it will just happen all over again when he's reintroduced. If the barred is as exceptional as you indicate (any pics? I'm always curious about any big healthy Rock...) then just keep him separate and use him for breeding. Maybe try him w/ 3-4 hens of his own and see if he's still snippy w/ them w/o the pressure of the other roo's. You will probably also need to separate the other 2 roo's as well. Keep your favorite of the two (sounds like the Sussex) and quarantine, eat or give away the other.
You can always add more hens in the spring but it will be a while before it did anything to change the dynamics of your flock.
Regardless though, good luck and hope you have a mild and uneventful winter.
Take care, sk