Great link Martyn.
I've been looking for an adjustable with a 2" jaw. I had a spot of bother with the central heating pump in the spring. It stopped pumping and is really (not) handy to get at. Basically under the lounge floor between the TV and chimney breast. The good news was that the carpet, underlay and floor came up really easily, and the pump has isolating valves either side. They were well corroded but gave up to some serious attention with penetrating oil. My problem was in not having an open ender with a 2" jaw to undo the main unions, so I had to improvise, while laying on the floor half submerged in the footings. It eventually gave in to heat and hammer and a motley collection of Moles and Stilsons. Every tweak caused a leak at the unions - very testing evening, that was. I very nearly gave up, and that's not something I do often. So I promised myself a decent pair of adjustables, although the price is a bit eye watering!!!