We use Stair Chairs, and Power Pros. Since our system has gone completely to this we have not had one back injury. Prior to that OJI(relating to backs) were costing approx 60-65k a year per person who filed, and we had amybe 3-4 file a year? The stretchers and Stair chairs have paid for themselves. And when stryker finally releases their now system that reaches out a claw and picks up the stretcher for you we will also go to that, or so I have heard.
The Power pro is heavier, but with all the hands on scene there is no reason one person should lift by themselves, therefore the weight does not matter. Also, we never have to carry them up or down any sufficient amount of steps because we carry Stair Chairs and Scoop Stretchers that work wonders at getting someone out of a place that has stairs.