I've read about the horror stories. The good thing about this one is that it was set up by someone who wrote a book on the subject and the last owner used peanut oil exclusively, for long distance 3-8 hour trips on the highway. I've only run one tank of canola myself.
In my limited research into veg + tdi, I've seen that a lot of people just say no. The people that say yes say 1) highway and 2) Rocketchip 2 Euro.
It does use a little oil, nothing too crazy as far as I can tell, definitely no oily smoke when accelerating or shifting. A poof of blue on the first start of the day. There is some oil in the intake piping, a film really. I found no puddle in the intercooler but I also WOT every time I get on the highway with an up to temperature engine.
Do you think a compression test would boost confidence? I don't have a tester for diesels but I could possibly buy one in the next couple weeks. I'm not opposed to bringing it to a diesel shop for an interested party either.
I also have an extra set of pop tested injectors that have never seen veg.