Hell Yes I believe removing the Health Cost of Noble Sacrifice as a Set Bonus should happen. I would GLADLY trade the extra 50 focus I get from the 4 piece set bonus for it. I don't need that extra 50 focus, when I'm down to 50 Focus crap is liable to hit the fan.
I consider myself to be "decent" at managing my focus and when crap starts to get a little sour in Ops I find myself practically depending on the Healing Trance and Noble Sacrifice combo to keep up with the damage being dealt out but it can be in vain if I'm just killing myself to keep someone else alive when no one can afford to go down. Granted this is a relatively uncommon situation but still it would be extremely useful.