Yeah, that's pretty much my feeling on the issue too, but I do like overkill
The argument going around in my head for sli is that it'd be an "easy" upgrade path further down the line, just to get another card to stick in there. On the other hand, by the time the second card is cheap enough to be a decent upgrade, I can almost guarantee that the card 2 or 3 generations down the line will probably be more powerful as a single card than the two I'd get in my PC, so I'd be better off just replacing the card.
Anyhow, my choice has been whittled down to this DFI T3R, or the upcoming Foxconn Avenger. I like the T3R's cooling solution, and DFI lately appear to be producing good motherboards. I also like the Avenger, particularly for the (extravagant and possibly useless) front bay that you can measure temps, voltages and speeds, as well as change speeds and voltages on the fly. Another thing I lika about the bay is that it's totally unconnected to the OS, it is just a part of the mobo.
Anyhow, I'll have cash in a few days, it's either a game of patience waiting for the foxconn, or give in and buy the DFI as soon as I can get it (imported from germany, or wait a bit for it to become available here).