Running B5 here in Las Vegas for the past six months now. Nothing but good things about bio-diesel. I wish we had a higher percentage available. It costs about 25 cents more a gallon but I am willing to pay that in order to make a small difference and to treat my 7.3 engine. I really like the idea of turning Nevada into a bio-diesel production facility using the algae method. Do a search on Google for this very innovative method and I think we can (if we want to) solve a huge part of our oil dependence problem.
I've been on B20 for close to a year now. There are tons of reasons to run bioD (a little cheaper here, lubricity, lower EGTs, as well as perhaps some environmental benefits) but the way I look at it, any $$$ of mine I can keep out of the hands of middle eastern nations is a good thing.