I don't think there's any way to know what hit if any any player will take. Most times there's no hit. Sometimes it's big. I think WIS says MakeUp has a lot to do with it.
The best guideline is never demote any player you really care about, unless you pair it with an injury.
The pairing of players matters. I got a hit when I called up Player X when Player A went on the DL. Then Player B went on the DL and I called up Player Z. When I took Player A off the DL, I demoted Player Z, figuring there wouldn't be a hit since he was brought up when a player went on the DL. I was wrong. Player Z got a hit because he wasn't demoted when Player B came off the DL.
Illustrating how silly the entire thing is. I can't believe anyone not only thought this was a good idea, but then took the time to write code to make it happen.