The entire concept of using JetBoost immediately after being Force Charged is dubious. Since you are rooted for 2 (usually 3) seconds after the Force Charge, your lack of movement means you negated nearly the entire benefit of the JetBoost's snare. Moreover the Vengence/Vigilance Warrior/Knights will be immune to ALL the effects of your Jet Boost at that time.
You are better off eating the initial damage and then then using Jet Boost after you are no longer rooted. At that point, then you can get some separation from the melee attacker.
Now if they changed JetBoost so that when you used it, it removed all negative movement effects (just as the Sorc Sprint ability does), AND allowed it to override Unstoppable/Unremitting, then you might be on to something....
Would defeat the entire purpose of Vigilance/Vengeance. There would be literally no reason to spec anything but Focus.
Mercs/Mandos need more escape mechanisms and means to alleviate cast time dependency, not utility vs 1 spec that isn't even FOTM. Rocket Punch should provide a short knockback baseline, with talents adding root would be a good start.
Chance to make the next skill instant cast (once per X seconds) when being hit would also help a whole lot. Reduced damage from under stuns (a la PT's stabilized armour) would be just fantastic - I'm surprised that it isn't as wide spread as it should be among classes vulnerable to CC.