In a pinch, a GPS is worth a ton. Get someone to the top of a dune and use their cell phone to dial 911 with the coordinates and waa laa, help is on the way.
There are not that many race radios compared to those that don't have them!!
Most low power radios are line of sight, meaning that if your behind a dune on the south side it will be difficult to get your message out. With your cell phone, try to aim at Ibex pass. north towards Death Valley on 127 for those So CAl folks.
The ultimate rescue device would be a sattelite cell phone with GPS!
FYI.....I carry a smoke bomb, a mirror, a first aid kit, flashlight, multi tool, rescue whistle and a strobe light, compass and knife, gps and cell phone and maps at all times. And a beer of course!!!
It's overkill but that's because of my search and rescue history!