Great point and all true except for this point,
Due to the methanol (approx 20%) it does have solvent properties so you'll be required to change your fuel filters and replace rubber seals and lines with synthetic ones.
the solvent properties of bio are inherent to the bio itself, as properly washed and dried bio has no free methanol in it.
When processing vegetable oil to make biodiesel you do add methanol, 22% actually, lye (aka KOH or NaOH as a catalyst), and heat.
After the process is complete you drain glycerin, then water wash the bio, to remove any leftover lye and methanol.
then the biodiesel is dried to remove the water.
The process is known as transesterification and breaks the bond of a tri glyceride chain (molecule of oil) and bonds a methanol molecule to each glyceride chain. The end result is that methanol replaces the glycerine on the molecule and for each tri glyceride chain (large molecule of oil) you end up which three single chains (individual chains are smaller) of biodiesel hence the lower viscosity for the same mass.
An easy way to think of it is like a bag full of oranges. If you tried to pour that bag it would have a certain viscosity, on the other hand if you pealed the oranges and broke them into orange pieces it would be less viscous, but you would have essentially the same material. It's not the perfect analogy, but you get the idea.
Anyway I supposed I've turned this post into a book, sorry about that.