I remodeled my mother's bathroom a year ago. Moved the toilet so there would be enough space around it with the new shower I installed. It was in the same room, only needed to be rotated and moved a little bit (a few inches over and back). The old piping was heavy duty cast iron...plaster ceilings beneath that I didn't want to chop out (I later did out of frustration to get it to work), and no clearance to work in the joist bays. It was a major pain. So, there is no easy answer to your question...it could be a piece of cake, it could be a major pain, which could require tearing out floors, ceilings, and walls. It's one of those things in that you just have to be there to say.