Purely anecdotal, but I've heard from a mechanic family member that the big three can't make an engine last past about 100,000 miles on pure e85. It's worth more research though.
I'm surprised that you're getting better numbers on e85. I've never seen it considerably cheaper than normal unleaded (in fact last time I saw it, it was more expensive). And like you said, it doesn't have the same energy density of gasoline so the mpg are worse.
I'm also not a huge fan of using food stock for fuel unless it's a last resort. I'd rather see more emphasis on things like longer range ev's fueled by solar power.