Brad, yes it's a very rare option. One reason why I snatched this one when I saw it come up.
Well the 996TT will be listed today, a few thoughts after driving it for several weeks. The car overall is just as fantastic as I expected. It's everything great about a standard 996, just turned up to 11. The power is fantastic, and the delivery is wonderfully linear and smooth. It just feels like a bigger motor, lag is nearly impossible to detect. The Mezger engine has a little air-cooled character to it, it has a little raspier voice than the M96 you'll find in a standard 996. It sounds almost identical to an air-cooled car at idle.
I've often read of the 996TT being criticized as more GT than sports car, I can't say I believe that to be the case. It feels light and tossable, and the limits are certainly higher than anything you'll ever approach on the street. Maybe in a hardcore track environment, but even then I think it would hold its own. I suppose it's GT in the sense that it's comfortable and quiet, I can easily picture myself taking it on a long road trip because it devours the highway.
Really my only criticism is that the packaging is such that everything is harder to get to, which is standard Porsche turbo. The spark plugs took two hours of removals to be accessible and the fuel filter took some strong cursing to replace. Nothing too horrible, but worthy of note.
So overall I loved it, pretty simple. It's one that I would definitely keep, and feels special. They are pretty good deals at the moment, I can't see them staying cheap forever.