Grand County EMS in Colorado also received a grant from US Smokeless Tobacco a few years ago. They have put much effort into a rescue pod and upgrades to the unit. I would recommend contacting Deputy Chief Trevor Denney at 970-887-2732 or email@example.com for information on what they have done as one possibility. (I don't think he participates here...)
We at AMR south mississippi have both I prefer the polaris others the gator, The polaris in my opinion gets around better but the gator gets through things the polaris wont. So I would say for serious off road use gator, but if you have to get around quickly and dont have to regularly use it in muck then the polaris is the way to go..
I don't know exactly what your agencies are specifically looking for but you might try looking into an Argo. They are amphibious vehicles. You can add accessories to them like a windshield and rollcage. Also they make stretcher mounts for the vehicles that can accomodate things like backboards and smaller type stretchers. The back of the vehicle is an open area. It can easily accomodate a patient and at least 2 technicians (this is with the stretcher mount in place). These are very nice vehicles and if you are in a rural area, these vehicles are rugged and built for various terrains.
We have a Polaris with a Kimtec Rescue body. I love it. It has paid for itself many times. We use it to cover the majority of a rails to trails, and during many large events here. The unit has done some major off road rescues. Some of the features that it has are: 6 wheel drive capable, seating for 4, one tech with the patient. capable of going 45 miles per hour, siren and light package from the factory (Kimtec). will be able to go through 2 feet of water. winch for front or rear. we have also included on ours a canopy for the back and a windshield from the Amish. many of our neighboring departments have seen this in action and have gone ahead and bought one for themselves. We are also able to stock this unit to the New York State Department of Health 800 for use as an ambulance.
We have a diesel Gator tricked out with a MedBed. Used mainly for Special Events ( Fourth of July Fireworks) and Little League World Series, but we also have a plow blade for it - one of our guys deployed to Katrina and saw a benefit to being able to move debris out of the way. So far no problems with it. Have no experience w other products.