Hard Target upgrade and the general TTK
First, I want to talk about the Hard Target upgrade and how it is too overpowered. The speed support classes gain from the Hard Target upgrade makes them too difficult to kill, and allows supports to sprint away too easily.
I would also like to add that the speed from Hard Target stacks with Engineer's double time. (Correct me if I am wrong)
I think giving a speed boost simply for taking damage is too rewarding with very little effort on the supports side. I would suggest making Hard Target behave like the Fallback upgrade.
A major thing that makes Hard Target so good is the overall high TTK. Most classes cannot deal damage fast enough to stop a speedy Hard Target support from escaping. The TTK is still too low; so low in fact that attack classes struggle to kill supports. This has been said before, but adding damage dropoff would be a safe way to allow classes to deal more damage without making the wrong classes too strong at range. I find the PVP almost unplayable because of how low the TTK is for most classes.
NOTE: GW1 and 2 still have a lower TTK than BFN, and those games didn't have sprinting.