Using Bio-D is perfectly safe for your fuel system and you engine in general.
If you discover you need to go to the dealer for a warranty repair, its not likely they will ask you what fuel you are using unless your advertising with a huge window decal that says "This truck runs on French Fry Grease". And you can always top off with diesel and thin it down a bit on the way to the dealer.
It is expensive, yes but you are still cutting your dependance on imported oil when you purchase it. So that alone is enough for me. I use the vegiostroke but still have to buy a tank of diesel every 2500 miles or so and if i could buy bio-d in OK, i would but as of yet, there are no stations around here selling it.
Go for it.