My Kitsune build and Blackbird build can jam at over 100km Optimal, I even have one "For Laughs" build which has an Optimal of 134km, Way more then any Sensor Damp I can find in PYFA, and this is with a strength enough to Perma Jam Frigates, and have up to 62% chance on a Crusier (according to EVE Uni's charts and some math) but yes, I am aiming to focus on a Rook, so that is like 42km with Racial optimal I think, But yeah, close range as a focus, but it isnt the ECM Rule. That and an in fallout Sensor Damps can 'Miss' which is the same as a ECM failing its chance for all intents and purpose, no? ECM just has the Dice roll all the time with a 50% hit to the chance in Falloff, where as other EWAR is 100% working untill falloff, then it has a 50% chance to fail, or have I gotten that wrong? Lots of info in this game, cant get them all right