Cars prior to about 95 or 96 often do have issues with rubber seals breaking down. Most diesel vehicles post 96 have Vyton seals in tanks, lines, injectors, etc. Filter changes aren't a big deal, and the parrafin is usually leftover residue from good ole #2. Run a tank through of the bio, swap the filter, and life is good.
There are probably some retrofits that'll be required from aircraft to aircraft to account for this, but in terms of a turbine engine burning biodiesel, I can't imagine much difficulty there. Biodiesel and regular #1/#2 aren't all that far apart in terms of viscosity and are miscible in any ratio.
I guess what I'm getting at is this shouldn't be viewed as though somebody perfected cold fusion in terms of technological achievement.
FWIW--I've got about 75K miles worth of biodiesel through my 2002 F350, and it runs like a champ...and smells like Cuban food out the tailpipe.
