I returned my conversion kit the other day. I really don't think that I need it. My stock 01 dakota (4.7L v8) has taken a liking to e85 with no conversion and no check engine light. I'm positive that the summer blend is out and I haven't had problems (yet). I noticed it when it was still cold here and it started harder than on winter blend about 1.5 months ago. I drive alot, usually 1 tank every 4-5 days.
Gasoline: 18-20 hwy
E85: 13-16 Hwy
The one drawback I did find with dakotas, is the fact that the fuel filter is in the fuel tank as part of the fuel pump. I haven't done anything with it, but I am concerned as I have 180,000 miles on it.