Listener reports from the Dallas/Ft. Worth Metroplex seem to indicate that the DEA is starting to use some of it's new P-25 UHF frequency assignments there.
After many reports from the Houston area and other Gulf regions of the new UHF frequencies, reports are that 413.9750 MHz, NAC156 is in use around DFW. The original UHF channels are also still in use in analog mode as well.
For a complete listing of what's been found on the new UHF channels so far, check out this previous blog post:
http://mt-fedfiles.blogspot.com/2011/02/more-new-dea-uhf-p-25.html