Thanks, magnus, for the info.
We had a demo today. Loading a log looks like an acquired skill, which the demo guy didn't really have, as he didn't seem that used to the machine. Having said that, we managed to drag a half ton log around anywhere the operator could go, through brambles, over stumps and piles of brash. The only thing it struggled on was getting over other logs, as the tracks slipped. I'm told you can fit spikes to the tracks, which would have helped. This one was as fast as the operator could go..on a clear ride, it would keep up with me almost jogging. I thought it did pretty well, considering it weighs less than half a ton