I was also very skeptical. During the phase out of "good # 2" diesel, I was trying to stay away from the ULSD on a cross country with my 3rd gen Dodge pulling a 10,000 lb trailer. I found the ULSD to be about 1 mpg less than the "old" LSD. That truck was very sensitive about different fuel. "Good" fuel from an interstate truck stop and it was a powerhouse. "Bad" from the corner gas station with the pump near the corner and it was a dog. It did not take long for me to plan my fuel stops better.
I had a bout of forgetitis and wound up at a Love's truck stop and all they had was biodiesel. I had to fill up and I was suprised. The truck ran great.
Our supervisor for the county highway dept. told me they run biodiesel all summer, but switch to ULSD in the winter months. He told me the lubricity is better with the biodiesel and they have had no problems.
I believe that just like the concerns with "regular" diesel, if you get it from a retailer that moves a good quantity of fuel, and change fuel filters on time, you should have no problems.
I still would not use it up here in the winter. Mr. Rudolf Diesel was a believer in biodiesel before it was biodiesel. He called it peanut oil and that is what he first used in his "Diesel" engine.