I have been looking and this is the only official answer I have been able to find:
a 25% loss without EMJO is needed to jump a ship
http://forum.astro-galaxy.com/index.php/topic,8464.0.html75% crew integrity without EMJO, 70% with EMJO MK I, 64.25% with EMJO MK II, etc...
or to look at it the other way:
25% loss without, 30% loss with MK I, 36.25% with MK II, etc...