Hello again!
By playing a little today i noticed a "glitch" involving "fast walk/steal"
Normally you can not fast walk through a crowd since you will steal from them and screw up the mission. However, if you (from a distance) hold the attack button with hidden blade equipped and THEN fast walk (I think it works in any order), Ezio will be able to fast walk without harming or stealing from anyone.
Hope this helps someone.
EDIT: I just found out this also works while gently pushing people around.