I think we all have seen them do the unexpected. I personally think that some claims of string jump are actually due more to plain old coincidence.
Not always, of course, but sometimes on these closer range cases I think it might be either a combination of factors or coincidence. One thing I am sure of, when it comes to deer, there are no absolutes. I also think we need to make those range choices on a deer by deer basis. Like Dnk says, head down and feeding is a whole lot different than a nervous one that you can kinda tell doesn't really want to be where he's at to begin with. I kinda respect Beebcl for admitting that losing a deer really bothers him as it should us all.