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My experience with www vs non www is that both can rank just fine, but it does seem though that the non www's are at a disadvantage since many linkers will add the w's on links leading to non www domains, I'm guessing just out of habit.
2 of my domains are well aged (9 and 4 years), both have many natural one way links from quality sources. Neither had 301's from www -> non originally but were added a year or so ago. Even after the redirects were added, many people will still link with the www's. I'm not at all convinced that the redirects are carrying the full weight of those IBL. Neither of those are ranking well at all the last 2 years (falling in and out of supplemental hell a few times, never regaining ranks). Both are listed in the SERP without the www.
Another site I own is also 9 years old, lots of natural IBLs but fewer authority sources. I originally didn't use www either, over the years so many linkers added them that now the cannonical url is with the w's in all engines. Around 2 years ago I realized this, gave in and now use only the www version. Ranking is holding fine.
There could be other reasons for the ranking problems, but any new sites I make, I add the w's right from the beginning to avoid potential problem. So far (knock on wood) they are doing pretty well.
Another listing from the domain can be found on the second result page. This is a very popular query for its sector, and for a "made for spam" domain to eat up 2 slots in the top 10 makes me inclined to think that either this technique is the ultimate, or Google would rather we click on the highly targeted ads rather than on those pesky "organic" results. I know we all have to make a buck, but come on...
I have a domain "three-word-phrase.com" that ranks well in a competitive sector, but I don't have control of the non-hyphenated version and I sure wish I did. The hyphens work just fine if all someone has to do is click a link, but they're a major impediment for offline promotion.