Just fitted Trax panniers on SW Motech hangers, took about an hour going slowly. All fitted together nicely with clear instructions ( only a couple of pages so even me as a bloke thought it worth while to look - big pictures ).
They look really wide on the bike, because the bike has a narrow rear end. They measure 32 cm out from the outer edge of the Grab handles. Shame you have to buy locks separately and I did not bother with the fancy (expensive) locks to lock carrier to bike, shall just use a cable lock.
They do seem to be nice quality - just need to put them to the test.