[johnchristopher]

> Maybe on paper. I wonder how much this is used.

I think as general rule of thumb for all intents and purposes it becomes a problem when you don't have money (or do criminal stuff).

> You may live in the other EU country as long as you continue to meet the conditions for residence. If you no longer do so, the national authorities may require you to leave.

> In exceptional cases, your host country can deport you on grounds of public policy or public security - but only if it can prove you represent a genuine, present and sufficiently serious threat affecting one of the fundamental interests of society.

> The deportation decision or the request to leave must be given to you in writing. It must state all the reasons for your deportation and specify how you can appeal and by when.