Since I got to roughly 50% ethanol per tank, I've found that drivability has suffered (much more hesitation), cold start is an issue (even at 55 degrees, the open loop portion of startup is rough, the car almost stalled once), and mileage isn't great.
So I've decided to run a couple of tanks of regular. This will allow me to get some good data on mileage and LTFT with low ethanol content. It's been a long time since I've run regular, and I don't have this data.
I'll probably run a couple of tanks ot premium as well, just to compare.
Then, more than likely, I'll run E30 through the winter.