I think that I'd rather put more effort behind finding a way to redirect a non-www to the www version (or vice versa) than to contact webmasters who link to you from highly trafficked websites. This seems like more of a temporary solution than a long term one.

Also, these links may not even be the high value ones in terms of link power, so if a visitor can access the right content from that link anyway, I don't see as much of a reason to contact them and trying to get them to add/remove three dubs.

I like your choice of referring domains, though. :)

Agree with shockley. In addition, in most cases I've checked these days, Google already knows that the www version is the same as the non-www one.

Which makes it yet another amusing thing that so many SEOs focus on when it's no longer necessary.

I agree with Shockley regarding "put more effort behind finding a way to redirect a non-www to the www version (or vice versa" but Jill's comment is just plain wrong and bad advice. You said it yourself Jill that "in most cases you've checked these days, Google already knows that the www version is the same as the non-www one" which certainly is not a definitive statement or else you would have said in all cases.

Saying "in all cases" would be false because I am currently working with a major retail brand who came to us with their entire website indexed in Google under the www version (which was the preferred) and the non-www version due to faulty redirects, and the different versions were ranking for targeted keyphrases. To say it's no longer necessary to check, at least at the very outset of a campaign, is misleading and misguided advice to be providing in such a forum.