Well I GOT THE BUG and want to build a new coop - one for some Cochins we'd like to get to live in separate.
We have an 8 ft long by 4 ft wide run and a 4 ft by 4 ft by 3 ft tall coop upstairs, we got two Wyandotte hens and a Bantam Cochin roo... On a rainy day like today the covered half of the run is a little crowded, if they had to stay like that for days on end it'd get real old.
Based on your dimensions I would think your guys are in a very healthy environment and would leave it as is... or maybe get a couple more bantams at best... If I have learned anything in the last 6 weeks (I am a noobie) it is that new additions to the flock can create a situation where personalities can clash and you have pecked on hens... Best to give them as much room as you can. After seeing this sweet Bantam Cochin female all pecked up last week I learned to be more cautious about the environment I bring newcomers into... It broke my heart to see this warm hen so pestered...
I am sure those guys you have really love all that walking around room...
Good luck deciding,
Michael