I have been running E85 daily in MN for close to 2 years. Probably 20-25k miles. I have a wideband O2 gauge to monitor AFR's and they really don't vary much between winter and summer blends. I would highly recommend this gauge.
I have never put pump gas into my car since switching to E85. About a year ago I pulled my injectors and had them tested and they all checked out fine. I don't have any start up issues in the cold.