I can add a personal story to this thread.
I broke my back ten years ago. By some miracle, I was not paralysed, however, I cannot walk or stand for very long before I either temporarliy lose the use of my right leg or occasionaly, both legs,or the pain gets too much to bear. I need to use an electric wheelchair to get around outside.
Back in September, my wife and I went Pembrokeshire (West Wales for you who don't know UK gegraphy) for a short holiday. While there, we visited an iron age hill fort at Castell Henllys. It has been excavated and partly reconstructed to show how the Celts lived in pre-Roman Britain. As it is a hill fort, it is on top of quite a steep hill. The car park and visitor centre is in a valley. I tried to ride to the hill fort in my wheelchair and failed in spectacular style. Even going downhill I couldn't control the wheelchair very well. I gave up and borrowed their Tramper.
The centre had a Tramper for the disabled to use if they or their wheelchairs coudn't cope with the steep tracks. It was free to use and hauled my 17 stone (240lbs) bulk around the site with ease.
The site wardens used a couple of buggies for their work, one was a petrol powered sort of cross between a quad and a pickup, the other was an electric version. Neither of these vehicles could cope with the terrain as well as the Tramper. The problem I had to overcome was the controls. With my wheelchair I have a joystick and a speed control rheostat. The Tramper had a motorcycle type twistgrip 'throttle' and a switch to to forward or reverse and another to 'change gear'. I kept twisting the speed control to go backwards, but shot forward at relatively high speed instead, which was a bit buttock clenching when you are on the edge of a cliff.
If anyone is ever in the area,it is well worth a visit
http://www.castellhenllys.com/
Just to prove it, my wife took a photo of fatso in the Tramper. The picture was taken at the bottom of the hill.