I totally disagree about Ellen not doing anything significant in the fleet,
She was heavily involved in politics, moved herself into supporting Tom Zarek, repeatedly asked Adama about Earth, and how long it would take to get there. And least we mention all the influencing she tried to do to Saul to get things changed, done in higher up areas. Further, shes still recurring in his thoughts/delusions. He sees her instead of the Six in the Brig...and its forgiveness and comfort hes drawn to finding in her. And Also, on top of this, one of the utterances of the First Hybrid (Razor) was this: "The pain of revelation bringing new clarity and in the midst of confusion, he will find her. Enemies brought together by impossible longing. Enemies now joined as one. The way forward at once unthinkable, yet inevitable. And the fifth, still in shadow, will claw toward the light, hungering for redemption that will only come in the howl of terrible suffering." I think that Saul "finds" Ellen in the Six so to speak, they are "enemies Brought together by imossible longing". Keep in mind too that Cylons as we know it are capable of induring intense physical demands, Ellen tigh wasnt shot when she died....she was poisoned... and left behind. Maybe her body could have metablozied the poison after a while...and waking up after that, realizing what had been done to her and why...she'd have a MASSIVE HUNGER FOR REDEMPTION..and that redemption could only come in the "Howl of Terrible Suffering".
My two cents.