I prefer moving the map when the actor gets to close to the edge that way the map does not scroll around all the time when you are just moving back and forth for something... I don't know if it's just me but the other way I get a headache...
what Zaei said about the detached camera is something I think is were slick. You can program the camera totally free from the game action and than attach it the way you want for effects and all of this. (for example when you press a button and somewhere there is a door opening or something you could have a move over there and stuff) that way you would be able to have maximum flexibility and also it would ensure good code (it needs to be good otherwise it wouldn't work that way)