I would have a different answer if we had a two story house. My single story house is 1100 sq ft, including the garage. I hear my ds6 get up and turn on the tv, then get up when I hear dd or ds comes to tell me he's starving, usually about a half an hour later. It means I get to sleep in to a lovely 7:30 am sometimes :)
We also consider this a privilege he earned by making responsible choices. If we found he watched something we had not approved (I check the Netflix history and he has a pretty short list), he would lose the privilege, of the tv and being able to get up alone.
Before ds was 5, he always came and got us immediately. If he had to go as far as downstairs, I would not allow it yet. And he is still not allowed to go in the kitchen, that is the one room we continue to keep gated (though more for the dog than the kids at this point). My dd2.5 is definitely not allowed to get up and roam around the house without a parent.
Like I said, once school starts this only happens on the weekends, no tv on school mornings and I prefer to be up earlier than everyone else.