I have a site that used to rank #1 on a couple of keywords based on a DMOZ listing alone. What that listing is worth has long since plummeted, as far as Google rankings go. Other sites I have listed don't seem to get any boost either, so I don't think it's a big deal any more (or much of a deal at all).
redundant to what? if you are asking if dmoz still provides value, the answer would be a resounding yes. dmoz continues to play an important role is shaping the architecture of the web.
temporary fluctuations in your engine of choice do not undermine the fact that dmoz provides structure and editorial discretion to a sea of information. as the web continues to swell, the importance of resources such as dmoz will only continue to grow.
is a listing in a relevant category from one of the most distinguished directories an asset? i would argue so.
Yes, as an ODP editor, I've seen thousands of ODP-listed sites and thousands of non-ODP-listed sites, and I agree that having an ODP listing doesn't affect Google rankings much if at all. I'm positive that Google ignores the cloned backlinks. So it's basically just one link.
It's free to suggest a site and takes 10 minutes to do, and a nice link from a themed site couldn't hurt, so it's not a bad idea to submit; but it won't change a website's Google fate, either. I really would not recommend spending more time or energy on it than any other single link from a relevant .org site.