What you mean by “insane”? Because she only deals 5% more damage tham Assault, and Assault doesn’t even need to be 50m away.
Also, considering that while cloaked, the Pred’s silhouette is only visible at 50m max, it makes that passive almost useless, unless the Pred is spamming the plasma shouder cannon and you can see the laser…
That said, to be a sniper, there’s no real incentive to use Isabelle over any other class.
To finish, the only thing Isabelle is actually a lot better than other classes (exception for Dutch87), is parrying, but considering that a Top Tier Pred player rarely uses melee, again it makes that shadow perk useless.