That sounds very much like an 'urban myth'. If you can cite some sort of factual reference for it, then fair enough- it reminds me of the story of everyones' house lights in Ongar (on the Epping to Ongar LUL line) dimming when a train accellerated on that section of track(!)
Its true, about the 92 anyway. Also the same for 91s in the Leeds area, when a 333 is behind a 91, it cant get full power from the wires. As told by a driver.