Sorry, that was a bit of an unhelpful reply. I don't care for Headstrong, because I find the short duration armor break okay, but not really that remarkable, but I know I'm somewhat in the minority there.
All the gold Cerebellas are good in different ways though, so I don't see a real reason to take a bronze to gold there, because the stats decrease of a natural bronze vs a natural gold isn't really outweighed by an really exceptional SA, unlike say Bad Hair Day or Rusty.
I have a diamond Headstrong so I guess I can make a comment with arguments. Hmmm, I guess that before people searched that classic combo of gold "Autoimmune" and "Armor Rating/Frost" in most of the rift maps, she was really good. Now she is a little bit useless because the logic starts applying Cripple so that would trigger Autoimmune and no counter anymore...