I've lived here at my place now since summer of 2011 and they've only been here once, but they didn't knock on my door. I heard someone sticking something to my door knob and then went down the stairs. When I opened up it was an invitation to the memorial. I thought that was odd, since my door was the only one getting it. I've also once got a handwritten invitation in my mailbox.
When I ask my JW mom (she lives I Europe, I live in the states since many years) she says they're still going D2D. But it sounds like she's traveling far from her home to do so, like taking 2 hour trips to go out to remote archipelago islands to knock on a few doors and make it into more of a scenic picnic trip for fun. Not like it was before when I was young and still lived at home and she was knocking on my classmates doors and embarrassed the living s*it out of me. Or was handing out magazines in the subway rush traffic.