I agree, Felix was no killer. Here are some things written about him soon after the murder by people who knew him well.
Letter from Ella to Nicholas and Alexandra (partial):
Arrived here to the news that Felix killed him, my little Felix I knew as a child, who all his life feared to kill, who did not wish to become military as to never have the occasion to shed blood- and I image what he must have gone through to do this, and how moved by patriotism he decided to save his sovereign and country from what we were all suffering. I telegraphed Dmitri not knowing where the boy was-but got no answer, since then it is in kind of silence....crime remains crime, but this one being of a special kind, can be counted as a duel and it is considered a patriotic act and for these deeds the law I think needs altering...
She goes on to basically tell how happy people were that Rasputin was gone, and they were 'kissing in the streets like Easter week'
Her last line is chilling considering what happened:
During the time of black clouds, may in the new year of 1917 the clouds be lifted, the sun shine in all beloved Russia, victories in the interior and exterior bring a glorious peace to you, our beloved Sovereign and all, all your subjects of which I am one- God bless you, God help you.
Your faithful sister,
Ella
I have always heard that after Alexandra dismissed her for her criticism of Rasputin, saying "I hope to never see you again", the sisters never did meet again. I don't know if this was a letter to N or both, or if they ever saw her again.
But back to the point of the letter, she who had known Felix all his life, (they were together a lot, and she was good friends with Zenaida) and was involved with him in charity work, did not see him as a bad or dangerous person.