If you are concerned about excess calcium for the roosters - here's what a poultry science specialist writing for the Ministry of Agriculture, Ontario has to say:
"It is also interesting to realize that most roosters today are fed high-calcium breeder diets, which provide 4-6x their calcium needs, yet kidney dysfunction is quite rare in these birds."
So he may well say that your adult roosters on laying feed should be okay since that feed has the same high level of calcium as breeder rations. The difference for youngsters getting too much calcium is probably that they have immature organs and, therefore, have problems with eliminating it.
My roosters eat some of the layer feed when I first fill up the feeder but after the hens eat it down to about half they can no longer get their head in the feeder to reach the feed therefore limiting them to just a certain amount. The rest of their diet is what they can scavenge when I broadcast feed them their treats twice daily of a mixture of grains.
I have a wire rack that goes over the top of the trough that's devised for a chain type broiler feeder. It keeps them from sticking their big ol' head down in the trough and standing there gorging their gut full all day. Those big ol' production roos can realy put away some feed and its not good for them and also wasteful. BTW this only works for big single combed roos.
They have a similar set up in the broiler breeder/layer houses where the roos have their feeders they can eat out of so much/many times a day, and the pullets have their feeders that only they can get in but they can eat out of theirs and the roos feeders also. The roos have a plastic apparatis that is placed through their nostrils about 4 inches wide that keeps them from sticking they're heads in the hen feeder but still can have access to their feed.
My freind tells a story about getting some of those roos when they swapped them out for newer ones every year or so. He got them to butcher for roasters, anyway someone came by once when he'd purchased some of the roos and they saw those nose pieces in them and asked where he got them and what kind of chickens they were(by the way they are gargantous, look as big as Turkeys) he told them they were African chickens, they replied, HUGH!!! He said: " yeah see the bones through their noses."
The only problem is feeding layer feed to young chicks. Adults have no problem getting rid of excess calcium, chicks who are in the super fast growing stage can develop organ damage because they can't filter it out fast enough. Again, adults-no prob.