Ken Magill posted today on "Why Fully Confirmed Opt-in Sucks." It's definitely worth reading, and I hear where Ken's coming from.
To "lose a subscriber" through their failure to confirm, that can really hurt when a list is pretty small. I should know -- I do know this myself -- because I managed the email list for my friend's wonderful jazz club in St. Paul, Minnesota, from late 1998 through mid-2006. (That would be the Artists' Quarter, by the way, and you should definitely go there next time you're up in the Twin Cities. Tell Kenny and Davis that Al sent you.)
For the AQ email list, I used COI from the start. It wasn't necessarily a political statement. It was born of using the tools I had handy. I had previously written a confirmed opt-in list management tool myself, so that's what I used.