Sounds nice, I've always liked the lopey cam idle. I wouldn't want it the fake way though, not through a tune. And especially not on a Voodoo engine since they already sound like pure sex.
Here's my take
ford and others NOW have variable cam timing to optimize output and drivability ( including idle)
my understanding is these tunes adjusts the cam phasing at idle position (leave the overlap which is deal and being used in the higher RPM) to get the classic "overlapping cam" idle sound.
So I see it this way......
your car already comes with an overlapping cam for high rpm performance.
Ford can retard the cam pairs appropriately so you get a smooth idle, or leave the fixed overlap resulting in the stumble...just like a classic fixed cam setup.
from this perspective, which would you prefer and which would you choose??
regarding emissions and warranty, that's a different story. I wouldn't risk for that. but if a tune can not effect this.. I would want it.