For what it's worth, I'm in exactly the same boat (bought it, it doesn't work out of the box. In fact, no mail gets passed when I turn it on - to be fair, I haven't had time to try to figure out why, nor have I contacted Darrell for help, so this could be pilot error, although it's not obvious what I'm doing wrong, if anything...)
I could probably figure it out, but since the e-mail interfaces change in 5.5, I may just write off the $50 and try an alternative like SpamAssassin. Anybody already have SA working on SME?