LB,
I know of this circumstance:
A friend had a number of roommates over a period of years. One of those roommates had his vehicle in prominent display at the friends house. While working on the vehicle the Dubs approached. This person told the Dubs they weren't welcome because a person living there was a former JW & did not want to be disturbed. The JW's did stay away until that roommate left and his vehicle disappeared. Then they gradually came back. This was over a period of about 4 years.
There are three things to consider that can change this:
1) Whether they actually honor the DNC w/o Legal Notices is a good question.
2) You also have to deal with their (real to sneaky) thought process of 'maybe somebody moved'. Somebody actually did in this case.
3) Somebody at the local KH could lose the records of the DNC.
Bottom line: it's a crap-shoot, unless you take the strong steps mentioned by Alan.
For a similar letter to Alan's check these 2 postings. This one has been posted a number of times and is not publicity sensitive. It is long and I recently posted it twice, so 'save the bandwidth'. Actually, there are several variations on the two posts.
http://www.jehovahs-witness.com/forum/thread.asp?id=18993&site=3
http://www.jehovahs-witness.com/forum/thread.asp?id=18983&site=3
I collect these.
Cheers,
Mustang