Free runner is perfect how it is, its a limited role not just because of the 6 slot limit but also because it is a job role that requires donator or trusted, so why make the only raiding role that trusted unlock weak?
The speed only affects how fast they can get from point A to B the speed doesn't help in combat what so ever unless its a melee fight because you cant run and shoot and when free runners ADS their walk speed is the same as others.
If the lowered HP and amour is implement then the free runners will just get destroyed 9 times out of 10 because with or without the speed buff because the lowered max HP.
Your logic is completely floored on why you want the change of HP and Kevlar based on speed because all of the government roles except mayor can have almost 2x the amour of any other non government class with no debuff given except for the juggernauts speed so if you want to limit the max HP on free runners it would only make sense to lower the max speed of all government roles depending on their rank and the amount of HP and Kevlar they spawn with.
you say ''Free runners have always been a topic of debate and easily the most hated job in game'' but cops have always been a dominating role not only with the guns and set HP they spawn with and not to mention cops get everything half price in the PD but also their ability to put someone in a cage for up to 5m not even counting the time it takes the cop to escort the person to the pd.
If you really want a balanced server make the cops either weaker or slower based on the Kevlar and HP like you want to do with the free runners.