People can't visit when the 3DS is off, so unless you leave it on with the gate open all the time they couldn't do any damage.
Well, I had planned to always leave it on, with wifi, and the gate open. I guess I am not doing that anymore.
Has this been posted yet? Chop down my trees if old.
http://www.telegraph.co.uk/technology/video-games/10096208/Animal-Crossing-New-Leaf-review.html
Old, but that reviewer and I have the same last name, so he must be good.