There are alot of people using E85 now around the hillclimbing family in Vic, and it has become a control fuel for varoius CAMS classes.
From my research I have noted the following:
As far as from the bowser goes I wouldn't trust it as it varies too much in blend, and it is also blended with 95 ULP from my research.
However, the stuff that the CAMS saloon car guys use is Blended with 98 ULP, and also contains all the anti corrosive agents required and from all reports works very well and also stores pretty well. It is far superior to the bowser variety.
I have looked at running it in my new engine. There are a number of factors you need to take into consideration.
Compression Ratio. If its low stick with 98 ULP, there will be little or no advantage in E85 unless you have the the compression to utilise it.
Cold start is a pain unless you have a very good cold start tune or well tuned carbs. Alot of guys still squirt ULP in to get their cars started.
Corrosion. Even though the the good E85 contains the anti rusting agents etc, over time it will still be a problem. Most people drain it and run ULP through the system after a race meet to prevent it, as you would with methanol.
All that asside, the guys I have spoken to running it absolutely love it, have had excellent results swapping over to it, and it smells great! Turbo engines love the stuff even better :)
Woz