I'm no good at the math but I've noticed I'm harvesting slightly more t8 rares now I have this cloak. I'm looking forward to getting the unicorn too, as that works in the same way iirc.
And of course the added effect of featherfall is very nice. There was me thinking I was going to have to farm EH for a fae cloak for all my alts!
I've not seen the random badger illusion yet though, which is way cooler than the rock! Anyone know if the badger illusion just randomly generates when you use the cloak, or just equipping it, or is it just a random zone-in thing?