I'm a volunteer ff for a fire/first response unit, and I also work with our radio man alot. We rely mostly on Motorola's, although alot of our guys go w/ yaesu or kenwood radios. The county Ambulance service uses Kenwood mobiles, while the medics themselves go w/ yaesus or motorola's so I'm guessing those are your top three. As a first response unit, one of they absolute best handheld radios is the motorola GP300. They are inexpensive, very reliable, and they give full power at long ranges. You can find them for roughly 200-300$$ online and that includes programming. As a personal favorite, for handheld, i use the Yaesu FT-50R dual band.
It is small, lightweight, waterproof, and also very reliable. These are purchased for $219.99 online and can be programmed by anyone. For a mobile radio, we use Motorola Radius or GP1225 (i think). 45 watts, and excellent quality.
When you are finished w/ your idea, please let me know more about it. You've struck my curiosity.