I have a 2012 Tribute Comanche with a 12" fretboard radius and I'm changing out the standard nut for a TUSQ XL nut from Graph Tech. I got the existing nut out to have a look at it and it's got a flat bottom. The area where it was glued in, though, is right in the middle so I can't tell whether the nut slot is actually flat and the glue just didn't spread to the edges, or if the slot is radiused and the glue didn't spread because the gap between the bottom of the nut and the nut slot got too big.
Here's a photo of the slot, with nut removed, and the glue:

And here's one of the nut sitting on the fretboard, to show the difference between the flat nut and the radius of the fretboard:

Flat vs. radiused will make the difference in which nut I order - by the way, anyone got any tips for getting that glue outta there?
Cheers
Pat