We also have a zodiac on our water rescue team and we also have one with my fire dept. Love them. Different sizes to pick from. Make sure to match the right motor size with the boat size. Higher horses doesn't necessarily make the safest boat. For lake use you might need a plane-ing fin. Also on WRT we have an ACB (aluminum) works great for diving off of and carrying gear, most rescues/recoveries but not as maneuverable in swiftwater.
If you're talking about the Cheoah River, then obviously a motorized watercraft is not an option for your department.
If you have any chance of taking the boat downriver, I'd stay away from the Oceanid RDC. The RDC is an excellent boat if you have to carry it to a single spot, surf out to a rescue scene, and surf back, but it does very poorly for downriver runs. If you get it sideways in a hydraulic, everyone goes swimming.
The NRS Otter is OK, but the multiple tube floor essentially gives you multiple inverted keels. The result is a boat that tracks very well in a straight line, but doesn't initiate turns as well as some of the competition.
The decision comes down to whether you want a slow self-bailing or a fast self-bailing floor.
The Maravia is in use by some of the best outfitters on the Ocoee. It has a very high rocker, turns the best of any big raft on the market, and still tracks pretty well in flat water. The floor retains enough water (slow bailing feature) to help punch out of big holes, but you can still surf the raft and it is very stable in big waves.
The high rocker will help you if you have to run either the right line or the center drop in Bear Creek Falls.
The Maravia has the most room for victims and gear of the Otter-sized boats, too.
If you're around the Ocoee, check out the forest green Maravia Rangers in use by Adventures Unlimited.
TARS also has an orange Ranger that we use as the gear boat for advanced swiftwater classes.
One of those will be held on the Hiwassee in late June.