An update on the decision to purchase a heavy duty brushcutter.
My wife found a machine like a wheeled strimmer and decided that's what she wanted. It's caller a DR Trimmer. More here:
http://www.drproducts.co.uk/files/Press/S28C-111041815150.pdfThe plus points are that it has a 4 stroke engine with electric start. My wife can't manage the recoil starters on a normal strimmer. Also it has a power drive to the wheels so you just follow it up and down slopes and bumps.
It takes nylon cord up to 4.5mm diameter which goes through brambles and heavy grown very well. It can also cut a lawn reasonably well. A half acre of rough lawn took about an hour. The results weren't up to bowling green standard but were OK for a play area or similar.
It doesn't cope with very steep slopes like the sides of ditches as the angle is too steep and it overturns if run along the slope and it is about 40kg so pulling it up and down is hard. Apart from this, small slopes and rough ground are fine. I have cleaned up some strips alongside a drive and tidied up an orchard area around fruit trees.
On this sort of work the cords (cut lengths) last for a couple of hours and it uses about 1litre of fuel per hour. It has an 8hp engine (I think) which makes it more powerful than most strimmers
On anything other than really heavy weeds it can go along at a good walking pace cutting about a 20" strip. On really heavy weeds and green brambles you can keep up the speed but cut a half strip (i.e. 10" wide).
There are a couple of accessories; a tree guard, a chainsaw disk and a little tool for digging holes for bulb and similar (e.g rows of seedlings). There isn't a standard brush cutter disk as the 4.5mm cord can cope with most weeds. I found it didn't like old tough bramble stems stripping the bark and shattering the stem rather than cutting it.
It also shatters tree guards and stems so care is needed round small trees, flower beds, etc.
I am spelling this out here as others might find a machine like this useful and it is rather different from the normal strimmer.