Is there a problem doing this? No not really your snakes are eating they are healthy and in the wild they will eat birds as easily as rodents. The reason we feed rodents is that they graduate in size as the animals grow. So from hatching to adult 3500 gram female there's a rat for that. With chicks there is considerably less flesh than a rat they are mostly legs and wings. So once you get past a 200 gram snake you might have to feed 4-5 chicks to equal the same food intake as feeding rats. And as the snake grows that number will increase.
Then comes the problem of if you ever for any reason have to sell or get rid of them. I can tell you I wouldn't even consider a BP who had been fed chicks for fear of having them get imprinted on them, I have enough trouble with Mousers.
Lastly comes babies. They don't make a chick small enough for a baby Ball Python and babies 99.99995% of the time have to have live prey to start. So your back to dealing with rodents.
If you never plan to breed or sell your current snakes then chicks will be fine..But it's when you plan to do anything else with them that a snag may happen.
Very valid points all. I do continue to mix their diet between mice and chicks. I will move them to rats as size dictates. I will keep chicks on the menu as long as I can. I don't fear imprinting because all my pets take birds and rodents with equal abandon. Thanks