Crissal Thrasher?

Unfortunately this is the only picture I got of this bird as it was quite timid and quickly disappeared into some dense brush. It was positioned in a shadow when I took the picture so it was fairly underexposed. I was able to pull out a fair amount of detail with image editing, but with the angle being from the back, there is missing details that would help with its identification.
Based on what can be seen, I narrowed it down to three birds; a Crissal Thrasher, a California Thrasher or a Le Conte's Thrasher. These birds all have gray backs, rufous or buffy undertail coverts and a large, curved bill.
I eliminated the California Thrasher pretty quickly as Las Vegas is out of range and Sibley states that the two rarely overlap. That leaves the Crissal and Le Conte's Thrasher. Of the two, I have to give the nod to a Crissal Thrasher because of its apparent darker gray coloration and darker rufous undertail coverts.
Please feel free to comment one way or the other on my conclusion.