Remember they are gamefowl, and know what you are getting. When you say std OEG's, do you mean the show fowl which are fairly uncommon, or do you mean American gamefowl which are often confused with them? If you go the show fowl route, they will be fine. But If you get a American gamecock and let him free range with other roosters (barnyard or game) you will have trouble, as anytime the other rooster gets too close the American game (this varies by lines, some will wait until the rooster is within a couple feet before he rushes him. Some cocks are not against running after another bird within 30 feet or more of him) he will want to fight him. And then the only outcome of that, is the barnyard rooster running away or dying unless you find them before it gets that serious. There is no possible way to keep them in a enclosure, as then he will chase the yard cock until he kills him or you separate them.
That is just what gameness means, the desire to fight (other birds, if they're aggressive towards you, eat them) until death. Which came from the aggressiveness of the junglefowl during mating season, then artificially selected to increase it by humans for thousands of years (or longer). Or that is what I have believed, perhaps there were some wild junglefowl who were as aggressive as today's games? No clue really.
-Daniel
