Last chase I used a D7 and Garmin GPS V. They sat on the dash and did a lot of dancing around during the chase. Today my students are helping me make a dash-mounted platform to hold the radio and GPS. They are mounted so I can read the displays from both devices, but it would be better to have a navigator go along to read.
The system is simple and starts up as soon as you apply power. That means no waiting to boot a PC or load software.