I figured I would give a late update. In about a month, I am returning to Colorado with the Flex Fuel tune. I have driven to Reno on about 1/3 tank of E85 and everything seemed to work just fine. I will give more butt dyno information once I get to Colorado. I do remember that things were definitely slower in the mountain passes, but mainly from a turbo lag standpoint.
I am keeping about 25% of the tank filled with 91 and the rest with E85. Cold engine performance is just kind of wonky on a complete tank of the stuff. That might improve with the new maps that, hopefully, will be coming out
Once things are warm, this car just flies.