I'm happy to see the change in direction with the T5. I like Shadowdancer as a hybrid tree overall, but Weird being the only option and not-usable by Rogues in their ED tree seemed wrong. What if the T5 made enemies vulnerable to sneak attacks while temporarily granting the party sneak attack dice?
I'm glad that anything you replace Whispers with will buff stealth-play. Something to break aggro and allow the rogue to sneak away (re-enter stealth without aggro) would be amazing- even if it has to be on a longer cooldown.