I'm not sure what class they were -- perhaps someone here can give some information -- but I didn't mind the passing of the DMUs that did the suburban services out of Paddington in the 1970s and into the 1980s. Compared to the EMUs, even the old ones such as the 4-SUBs, that I regularly used to and from Waterloo, they were hopelessly sluggish, with very slow acceleration: it almost felt as if they were decelerating when changing up gears. About the only thing in their favour was one could get a view forward through the front cab, so long as the driver had raised the blind behind him. Their replacements are a lot more lively, with acceleration as good as any modern EMU; the only drawback being the usual one about seats not matching the windows (but that applies to modern EMUs as well).