I had never seen one of these in the UK [member=3211]Anke[/member], possibly because of 'health and safety' rules, but they are common in France for cutting areas that the local farmer can't get to. Probably 10x faster than a strimmer- perhaps even quicker? Sold as a Tondeuse- Débroussailleuse (mower- brushcutter).
Ours is a Kiva Odyssee V2 with a Honda 200 engine, variable speed transmission, variable height cut and wheel differentials. Anything less isn't worth having because it will be a real handful to manoeuvre. Runs on three wheels, the front being a swivel and the rear are 45cm with solid rubber tyres. Basically a very beefed-up self propelled mower, but side eject. To cut brush (max 15mm thick) the front of the deck is removed so that the material isn't knocked over by the skirt. You can fit a deflector to the eject side so that the material is left in a neat row for gathering. There is another French make and Husqvarna used to make them. Extreme care is needed to avoid slicing your toes off- it has a 10mm thick hardened steel blade, so safety boots probably won't save them.