I repeat my question from another post
Without some way to make yourself faster than the average bear, how will thieves outrun guards?
Edit: On that token, that is something to be taken into consideration by the Devs. on OB it didn't really matter cause if you resisted arrest every guard in Cyrodill would flock to you. Even if you hoofed it from Bruma to Leyawiin you'd still have Bruma dudes chasing you, plus probably a few imperial soldiers. But with the new dialog system and (hopefully) no psychic guards, it would probably be a lot more..opportune to try to run.
Remember, armor slows your character down. So thieves will be in light armor, thus they will run faster than someone clad in heavy armor.