Well I didn't get a Butters (well not quite) in the end. I got one of these http://www.buttersuk.co.uk/productinfo.php?id=14 instead. Not quite as expensive as the 181 and seems quite well put together. hopefully it'll do me well for a few years to come.
it's quite nice to use. the only minor gripes I have with it are it won't take having the gas bottle I have sat on it as it flexes the case too much. and the adjustment on the wirefeed isn't quite stiff enough so it gets knocked out really easily.